State Primary Laws and the Ideological Composition of Primary Electorates

State Primary Laws and the Ideological Composition of Primary Electorates Barbara Norrander and Jay L. Wendland University of Arizona Abstract Previous research has confirmed that state primary laws influence the number of independents and partisans in the state (Burden and Greene 2000; Campbell, Converse, Miller and Stokes 1960; Norrander 1989). In general, closed primary states have more partisans and open primary states have more independents. More recent research also demonstrates that these primary laws not only affect the number of independents and partisans in a state but also the ideological orientations of these groups (Norrander, Stephens and Wendland 2012). Thus, in closed primary states the larger groups of partisans are more ideological diverse, while the open primary states the smaller numbers of partisans are more ideologically distinctive and polarized. This paper extends the research to the ideological composition of the primary electorates under different participation rules. Paper presented at the State Politics & Policy Conference, Indiana University, Bloomington, Indiana, May 15-17, 2014.

State Primary Laws and the Ideological Composition of Primary Electorates In searching for an electoral cause for the polarization of American parties, the finger is often pointed at primary voters. Primary voters are characterized as more ideologically extreme than general election voters, and this is viewed as especially true in closed primary states where participation is restricted to registered partisans. These views on the ideological extremism of primary voters are shared by reformers, journalists and many social scientists. Thus, Mark Siegel (2011) writing in The Washington Post directly links party polarization to the closed primary, while California State Senator Abel Maldonado describes voters in closed primaries as hyper-partisans (Kieley 2010). Social scientists adopting a Downsian view of the American electorate place partisans on the liberal and conservative ends while assigning independents to the ideological middle. Thus, closed primaries that restrict participation to partisans are depicted as having voters farther removed from the median voter than open primaries that allow independents to vote (Chen and Yang 2002; Gerber and Morton 1998; Kanthak and Morton 2001). Overlooked in these arguments about the composition of primary electorates is the influence of primary laws on the proportions of independents and partisans in the states and the influence of these laws on the ideological composition of these groups. The influence of primary laws on the numbers of independents and partisans in a state is well established. Beginning with The American Voter (Campbell et al. 1960), the impact of state laws on party identification has been empirically demonstrated. Additional research has pinpointed the effects of primary participation laws on partisanship (Burden and Greene 2000; Norrander 1989; Norrander, Stephens and Wendland 2013). These effects are such that closed primary rules encourage more individuals to register as partisans (e.g., party enrollment) and view themselves as partisans (e.g, party identification). In fact, a state with a closed primary format may instruct people when registering to 1

vote that they must designate a party preference if they wish to vote in a primary. For example, the current New York state registration from indicates To vote in a primary election, you must be enrolled in one of these parties --- except the Independence Party, which permits non-enrolled voters to participate in certain primary election. Having registered as a partisan, the voter in a closed primary state is highly likely to subsequently adopt a partisan identification, and as a citizen rather than a social scientist may not even distinguish between the two. Open primary laws have the opposite effect. State registration forms do not contain a space for party enrollment, so partisan attachments are based purely on individual reasons. In recent decades, such partisan attachments are attributed to issue preferences and an ideological realignment. Thus, in open primary states there are fewer partisans and they may be more ideological distinct. Semi-closed primaries, which allow independents to choose between the Democratic or Republican primary, function similarly to open primary laws and produce more independents and fewer partisans. Again, state registration sites may encourage such behavior. For example, the New Hampshire Secretary of State website explains that An undeclared voter may vote in a state primary or a presidential primary. You will be required to choose either a Republican or Democratic ballot when you go to vote. It further explains that to unenroll in the party after voting in a primary, When you vote on a party ballot in a state or presidential primary, you become a registered member of that party unless you fill out a card or sign a list to return to undeclared status with the supervisors of the checklist. Such a process encourages voters to register as independents to maintain flexibility in primary choice. Meanwhile, semi-open primaries which require all voters to inform an election official of their choice of primary produce results more similar to closed primaries with these states having more partisans and fewer independents. This last effect may be tied to the historical patterns of what is today classified as a semi-open primary. The public declaration format was the original method for a closed primary, before states began to use partisan enrollment on state registration forms (Berdahl 2

1942; Merriam and Overacker 1928). Further, the public declarations used in semi-open primaries may contain oaths of loyalty to a party and opportunities for public challenges. Thus, the four types of primary participation laws produce varying proportions of partisans and independents across the 50 states. Less studied is the influence of primary laws on the ideological positioning of partisans and independents. Norrander, Stephens and Wendland (2013), using general election exit poll data, find that the smaller groups of partisans in open primary states are more ideological extreme, resulting in more polarization across the two parties identifiers. The larger groups of partisans in closed primary states are more ideologically heterogeneous and the two parties identifiers are less polarized. In examining participants in the 2008 presidential primaries, these authors find the ideological composition of electorates in closed and open primary states to be identical. In closed primary states, partisans participating in the primaries are closer to their states median voters, while in open primary states the ideological extremism of partisan voters is offset by the more moderate orientation of independent participants. Presidential primaries, however, have turnout rates that are higher than other types of primaries, and this higher turnout rate could ameliorate underlying differences across primary formats. Thus in this paper, we analyze the effects of primary laws on the ideological orientation of voters in an off-year election setting. Theoretical Arguments In general, we expect far fewer differences in the ideological orientations of primary voters across primary participation formats than conventional wisdom suggests. This preposition is based on prior research that demonstrates voters react to primary participation laws in their party enrollments and party identifications (Burden and Greene 2000; Campbell et al. 1960; Norrander 1989). To illustrate this argument, we repeat our diagrams from Norrander, Stephens and Wendland (2013) in Figure 1. 3

Part A of this figure represents the typical assumption that party identification patterns are identical across all states. If this were true, open primaries which allow moderate independents to participate would have a more moderate primary electorate. Closed primary states restricting participation to partisans would have an ideologically more extreme primary electorate. However, Figures 1b and 1c fit reality much better. In closed primary states, depicted in Figure 1b, more voters identify as partisans and fewer as independents. Thus, restricting participation to partisans does not necessarily produce an ideologically extreme primary electorate. Figure 1c reflects the pattern in open primary states. Here the smaller groups of partisans are more ideologically extreme and a larger proportion of independents voting in a primary are necessary to balance off the ideological orientation of partisan voters. A second set of factors shaping the ideological orientation of primary voters is which groups of partisans and independents have an incentive to vote in a primary. Perhaps, only partisans, and especially strong partisans, can be relied upon to be consistent primary voters. If this is the case, than closed primary states would generally have a more moderate primary electorate than an open primary state. However, characteristics of the primary contest may encourage more voters, of all types, to participate. Thus, a primary ballot with a competitive race for a gubernatorial or senatorial nomination may bring out a larger number of voters from all partisan categories. In such case, we would expect fewer differences in the ideological composition of primary electorates, as the increasing number of independent voters in the open primary states would moderate the partisan voters in those states. Yet, a competitive primary contests may arise from a challenge by a more ideologically extreme candidate. In this case, the mobilization would occur for more ideologically extreme voters, whether they are partisans or independents. Finally, the primary of the majority party in a state generally has a higher turnout level, and thus, may have the more ideologically moderate electorate. Further, the majority party has a greater influence on the ideological positioning of a state s median voter as they constitute a larger number of these voters. 4

Individual traits also should be linked to primary participation, just as these demographic traits are a major determinant of who votes in general elections. People with more education are the most likely voters. Education levels also are related to political polarization, as more highly educated voters are aware of party differences and have sorted themselves better into the correct political party. Older citizens are more frequent voters, and this is also true for primary elections. Thus, if older voters have a unique political orientation, such as being more conservative, their greater presence among the primary electorates should affect the ideological composition of that electorate. While a gender gap exists between the two parties, some evidence also suggests an intra-party gender gap with female Democrats being more liberal than male Democrats and female Republicans being more moderate than male Republicans (Norrander 2003). Thus, the presence of more women among a state s primary electorate should alter the ideological composition of this electorate. Racial differences, between whites and nonwhites, could also affect the ideological composition of the primary electorate. Finally, two factors may be particularly important for the composition of the Republican primary electorate. Religiously conservative voters are a core component of the Republican Party and have preferred specific candidates in recent presidential nomination contests. As such, religiously conservative voters may be shaping the ideological orientation of gubernatorial and senatorial primary contests, as well. The mobilization of Tea Party supporters in 2010 also would shape the ideological composition of Republican primary electorates. Data and Methods Our analysis uses the 2010 Cooperative Congressional Election Survey to study primary voters (Ansolabehere 2012). The 2010 CCES provides what may be the only cross-state survey of voters in primary elections, other than presidential primaries. Thus, the 2010 CCES helps to fill a void where we know very little about the actual composition of primary electorates and how they compare under different participation formats. Further, the 2010 CCES contains a validated vote measure for both the 5

general election and the primary elections. The validated vote distinction is important, as prior work using these data reveal significantly less distinctiveness for primary voters when using the validated vote (Sides and Vavreck 2013) than simply the reported vote (Jacobson 2012). Our dependent variable is the deviation in ideological orientation between a primary voter and his or her state s median voter. The CCES measures ideology on a five point scale: (1) very liberal, (2) liberal, (3) moderate, (4) conservative, and (5) very conservative. Each state s median voter score was obtain from the mean ideology score for all survey respondents with a validated general election vote. Across all state, the mean score for the median voter ideology equaled 3.3 (weighted n = 54,487) with a range from the most liberal state (Hawaii median voter = 3.05) to the most conservative state (Idaho median voter = 3.76). For each validated primary voter the appropriate state median voter s ideology score was subtracted from the primary voter s ideology. We calculated these ideological deviation scores separately for primary voters reporting that they participated in the Democratic versus Republican primary. The mean ideological deviation score for Democratic primary voters was -.72 (weighted n = 5,922), indicating a more liberal orientation than the state s median voter, while the mean ideological deviation score for voters in the Republican primaries was.69 (weighted n = 7,875), a more conservative score than the state s median voter. Focusing the research on participation in a partisan primary excluded respondents from Washington State, which used a top-two primary in 2010, and Louisiana, which held a nonpartisan primary. In addition, Virginia does not provide voting records, so the 2010 CCES could not provide a validated vote for those respondents. Primary participation rules are the central independent variable. Our measure is based on the listing by Holbrook and La Raja (2008), with updates to 2010 and adjustments based on information from state election official websites. Appendix A lists states in the four primary types. Closed primary classification requires a state to ask for a partisan designation on the voter registration form and restrict participation in pirmaries to enrolled partisans. Classification as a semi-closed primary state is more 6

complex and diverse. These states also provide for partisan registration but allow for some type of participation by registered independents. Some of these states allow independents to vote in a partisan primary without changing their independent registration status. Other states alter the registration of an independent to a partisan upon participation in a partisan primary, although in some of these states, such as New Hampshire, a voter can easily return to independent status by filling out a form after the vote. Some state laws, and the U.S. Supreme Court case of Tashjian v. Republican Party (1986), allow for parties to invite participation by independents into their closed primaries. Thus, there may be a mixture of closed versus semi-closed primary formats across parties in a single state or across election years. The classification for the two forms of open primaries requires that a state not request partisan enrollment on its voter registration form. Semi-open primaries differ from open primaries in that the former requires voters to ask an election official for a specific party s primary ballot while in the later, voters receive a ballot for both parties and choose in private which ballot to mark. Other election laws can make this four-fold classification murkier. Some states have different primary formats for presidential primaries than for other primaries, with more closed primaries for presidential primaries. The use of mail ballots or permanent absentee ballot laws may obscure the effects of semi-closed primaries as independents, but not partisans, must communicate with election officials to designate which party s primary ballot to be sent. Other independent variables measure that nature of a primary held in 2010 beyond the participation format. Some contests are more competitive than others, and thus, should draw in more voters. As pre-primary information on the competitiveness of a primary contest is not available in a consistent format, we measure the competitiveness of contests for senatorial and gubernatorial nominations by the votes cast. Vote totals were obtained from each state s secretary of state or election board website. To measure the competitiveness of each contest, we modified the effective number of parties (Laakso and Taagepera 1979) formula to account for the closeness of the primary 7

candidates. A zero score indicates that no gubernatorial or senate contest occurred for a party within a state, while a score of one indicates only one candidate s name appeared on the ballot. Scores higher than one indicate greater competitiveness. The most competitive contest scores were as follows: Democratic senate primary 4.4, Republican senate primary 4.1, Democratic gubernatorial primary 3.9 and Republican gubernatorial primary 5.7. We also include a dummy variable for those states or party primaries without a gubernatorial or senatorial contest. Two more state-level independent variables measure majority party status and turnout levels. We measure majority party status based on the party identification question in the 2010 CCES aggregated to the state level. The CCES party identification question provides the typical seven-category scale from strong Democrat through strong Republican. We collapsed strong and weak Democrats along with independents leaning toward the Democratic Party to indicate the percent of a state s respondents favoring the Democratic Party. The same procedure was used to identify Republican adherents. To account for remaining varying levels of pure independents across the states, we measured Democratic majority party status by subtracting the percent of a state s respondents favoring the Republican Party from those favoring the Democratic Party. This provided us with a measure of Democratic preferences as a percentage of the two-party (the resulting variable varied from.30 to.84). The same process was followed to create the measure of Republican Party majority status as a percentage of the two-party support (varying from.16 to.70). We used these measures of majority party status to calculate turnout for each primary. For the numerator we used the highest vote total for either the senate or gubernatorial primary for each party in each state. A few states or parties had neither a senator nor a gubernatorial primary, so we made substitutions for another statewide office or summed totals for lower-level offices. 1 For the denominator we multiplied the majority party status figure times the 1 We used the U.S. House of Representative vote totals for both parties primaries in Montana, New Jersey and West Virginia. We used the same for both parties in Mississippi, but the ballot for the Republican primary covered only congressional districts 1, 2 and 4, while the Mississippi Democratic primary covered only congressional district 8

state s voting eligible population in 2010 (McDonald 2012). This denominator divides a state s voting eligible population into partisan leaning components and allows for comparison across states with and without party registration figures (Norrander 1986). This procedure provided turnout rates in Democratic primaries with a senator or gubernatorial primary ranging from 7 percent to 38 percent and for Republican primaries from 5 percent to 46 percent. Individual-level independent variables from the 2010 CCES survey included sex (dummy variable with one equally female), race (dummy variable with white versus all other races), education level, age and self-classification as a born-again Christian. An evaluation of the Tea Party also is included as a separate model for participation in the Republican primaries. 2 To test the effects of the different categories of partisans participating in a primary, we divided the CCES 7-point partisanship scale into a series of dummy variables: 1) partisans (strong or weak partisans) voting in their own party s primary, 2) independents who lean toward that party, 3) all other independents (pure independents and independents leaning toward the other party), and 4) opposite party partisans crossing over to vote in a primary. Own-party partisan is the excluded dummy variable category. To account for the sampling procedure employed in the 2010 CCES, we used the recommended weight variable. Our final model includes a mixture of both state-level and individual level variables. However, we have no expectations that the state-level variables will have differential effects across the various primaries, or in other words, we do not expect any random effects for these variables. Thus, our statistical models use ordinary least squares regression with clustering by state to produce robust standard errors. 3. For the Utah Democratic primary vote totals, the only available vote was for congressional district two. For the Democratic primary in Delaware, we used the vote totals for the state treasurer post. Finally, for the South Dakota Democratic primary the highest available vote totals were for three state house seats. The vote totals for Mississippi, South Dakota Democrats and Utah Democrats may underestimate the number of votes casts across the state producing a turnout value that is too low. 2 The CCES question is: What is your view of the Tea Party movement would you say it is very positive, somewhat positive, neutral, somewhat negative, or very negative or don t you know enough about the Tea Party movement to say? We recoded Don t know enough to say and No opinion answers with the Neutral category. We also recoded the direction of the Tea Party question so that a higher number indicated greater support. 9

Results The general ideological orientation of voters in Democratic and Republican primaries in 2010 divided by type of participation rules are given in Table 1. Entries are mean values for the ideological deviation of primary voters in comparison to their state s general election median voter. As expected, participants in Democratic primaries are more liberal than their states median voter, signified by mean values across the four primary types ranging from -.66 to -.86. Republican primary voters are more conservative, ranging across primary types from a mean of.61 to.77. However, contrary to conventional wisdom, these mean values by primary type do not all conform to the idea that voters in closed primaries would be more ideologically extreme than voters in open primaries. In fact, for the Democratic primaries, the opposite pattern occurs. Those who voted in a closed Democratic primary deviated the least from their state s median voter, while those who voted in an open primary diverged the most in the liberal direction. Results for the Republican primaries conform more to conventional wisdom. Those who voted in the closed primaries deviated the most from their state s median voter by being more conservative, while those who voted in semi-open primaries deviated the least from their state s median voter. The bottom half of the Table 1 shows tests of statistical significance for these mean values. Here the evidence is that the patterns of ideological deviations for the different participation formats for Republican primaries are not typically statistically significant. Only half of the pairs of primary formats are statistically different from one another. For the other half, one would conclude that ideological deviations for Republican voters are the same in closed and semi-closed primary states; and that these patterns are similar for open primary states paired with either semi-closed or semi-open primary formats. The statistical significance patterns for Democratic primaries are more numerous, with evidence suggesting identical ideological deviation patterns for semi-closed and semi-open primaries. 10

Yet again, while the differences in ideological orientations between voters in open and closed Democratic primaries are statistically significant, they are in the opposite direction of convention wisdom with more moderate voters in closed primaries and more extreme voters in open primaries. These mean values for ideological deviations of primary voters by primary type do not take into consideration other factors that could shape the ideological position of voters in these primaries. Voters react to the nature of the election contests, with more voters participating when races are competitive and fewer turning out to vote in noncompetitive contests. As turnout increases, primary voters, regardless of participation rules, may be more ideological diverse and deviate less from their state s median voter. Thus, we expect that more competitive senatorial or gubernatorial contests will result in less ideological extremism among primary voter and that overall turnout levels in primary elections should reduce ideological extremism. Turnout is generally higher in the primaries of the majority party in a geographic area, in part because their contests are often more competitive. Furthermore, the majority party in an area constitutes a higher proportion of a state s electorate, and their numbers influence the ideological positioning of the state s median voter. Thus, we expect a more moderate primary electorate as a party becomes a more dominant force in a geographic region. We test these hypotheses with multivariate models presented in Table 2. The first equation for each party s primary voters includes only the state-level variables, while the second set of equations adds in traits of individual voters. Beginning with the first equation for voters in the Democratic primaries, two of the primary participation formats show a statistically significance difference from closed primaries (the exclude category). Both voters in semi-closed primaries and open primaries are more ideologically extreme than voters in closed primaries. Participants in the 2010 Democratic primaries held under semi-closed or open primary rules deviated the most in the liberal direction away from their state s median voter. The nature of the primary contests appears not to have much influence on the ideological orientation of Democratic primary 11

participants, as the competitiveness of the primaries for governor or senate did not matter. However, in Democratic primaries with higher turnout levels, the ideological orientation of the primary voter is more moderate and less distinctive from the state s median voter. Finally, when the Democratic Party is a stronger majority party, voters in its primary are more reflective of the state s median voter. Looking at the first equation for Republican primary voters reveals a somewhat different pattern. Here the best interpretation is that primary participation formats have no effect on the ideological composition of the primary electorate (though this will change somewhat with the addition of individual voter traits). Once again, the influence of the competitiveness of the primary contest appears to be insignificant. However, if a primary ballot had neither a gubernatorial or senatorial contest, the primary electorate became more moderate and deviated less from the states median voters. Likewise, higher primary turnout rates and primaries held in states where the Republican Party was a stronger majority party also had more moderate primary electorates. While the state-level variable model for both Republican and Democratic primary voters contained some statistically significant effects, neither model explains much of the variance in the ideological orientation of primary voters. Only between 2 and 3 percent of the variance was explained. The remaining equations in Table 2 demonstrate that most of the ideological orientation of primary voters is explained by their own personal traits rather than by the institutional settings, as the R 2 values for the statistical equations increase to.22 to.35. The partisan orientation of the primary voter matters, with crossover voters being more ideologically moderate in both party s primaries. However, the overall influence of these crossover voters is diminished by their overall numbers. Table 3 lists the proportions of each party s primary that is composed of own-party partisans, independents leaning toward that party, other independents and true crossover voters from the opposition party and also the proportions in the traditional sevencategory party identification scale. Using the four-category data, true crossover voters by the opposite 12

party s partisans is less than 5 percent of primary voters, regardless of primary type or party of the primary. Further, the proportion of voters who are independents not leaning toward the party of the primary is also quite small in most cases typically less than 10 percent. The main orientations of primary voters are either as own-party partisans or as independents leaning toward that party. It is here that some variations are found across the primary type. The partisanship of voters in closed primaries is mostly own-party partisans and fewer leaning independents, while the partisanship of voters in open primaries is fewer own-party partisans and more leaning independents. Further, the variations across primary types are mostly in the movement between the weak partisans and independent leaning categories, as illustrated in the seven-category breakdown. Weak partisanship versus independent leanings are the types of partisan orientations that should be most influenced by primary participation rules. Individuals with weaker attractions to the political parties in closed primary states declare themselves as weak partisans and vote in their party s primary. In open primary states, individuals with a weak attraction to a political party declare themselves as independents leaning toward that party and still participate in that party s primary. Beyond partisanship, other individual traits affect the ideological orientation of primary voters. Among those participating in the Democratic primaries, whites are more liberal than nonwhites and people with higher education levels are more liberal than those with lower education levels. Older voters are more moderate than younger voters, and born-again Christians voting in the Democratic primaries are more moderate than other Democratic primary voters. Once these individual-level traits are entered, the influence of primary type becomes more pronounced and reflects the pattern shown in Table 1. Voters in the closed Democratic primaries deviated less from their state s median voter than did voters in the semi-closed, semi-open or open primaries. Once again, this is opposite of assumptions in conventional wisdom that views the closed primary setting as the one with the most extreme set of voters. 13

On the Republican side, the traits of individual voters also influence their ideological orientations. Here we see an intra-party gender gap, with women voting in the Republican primaries being more moderate than male voters. Race and education do not matter, but older voters are more conservative than younger voters. Religious beliefs are significant, with born-again Christians being more conservative in their political ideologies than other Republican voters. Finally, the last equation demonstrates the importance of the Tea Party to the 2010 Republican primaries. Supporters of the Tea Party constituted a more conservative Republican primary voter. Just as was the case for the Democratic primaries, once individual voter characteristics are taken into account the institutional factors of primary type matter more. Yet, the pattern for the Republican Party now reflects the pattern for Democratic primaries. It is in the open primaries that the most extreme ideological voters are found on both the Republican and Democratic side. In the Republican primaries, voters in the open primary deviate the most in the conservative direction from their state s general election median voter and on the Democratic side, voters in the open primaries deviate the most in the liberal direction from their state s general election median voter. Conclusions Conventional wisdom holds that voters in closed primaries should be more ideologically extreme than voters in open primaries. The restriction of participation in closed primaries to registered partisans leads to assumptions that these voters are hyper-partisans, issue activists, or ideological extremists. The presence of independent voters in open primaries is assumed to bring more moderates into the primary electorate. However, this convention wisdom ignores the influence of primary participation laws on voters perceptions of themselves as partisans or independents. Thus, closed primary laws produce more partisans who are more ideological diverse, allowing for this ideological diversity to be incorporated into the closed primary electorate. Open primary laws encourage more 14

individuals to view themselves as independents, leaving the partisan identity to more issue-oriented or ideological citizens. Thus, in open primaries, the presence of a larger group of independents offsets the ideological extremism of the smaller group of partisan participants. Our research based on voters in the 2010 primaries demonstrates that the ideological orientation of primary voters does not fit conventional wisdom. Consistently on the Democratic side, our data revealed that the most extreme primary voters, in comparison to their states median voter, were found in the open primary setting and the most moderate voters were in the closed primaries. The pattern on the Republican side was less pronounced, but when individual voter demographic traits were taken into account, again it was the open primaries that had the more extreme primary electorate. These contrarian results arise because of the interconnection of primary type with partisan orientations and ideological identities. When examining the partisan composition of the primary electorates, we find that between 81 to 94 percent of primary voters are strong or weak partisans or independents leaning toward that party. In closed primaries, there are more partisans and fewer leaning independents; while in open primaries, there are fewer partisans and more leaning independents. Political scientists have often speculated that weak partisans and leaning independents are often alike. Thus, their varying presence in the primary electorate under the different participation formats serves to mute the presumed ideological distinctiveness across primary formats. Finally, our statistical models reveal that personal traits of primary voters are a much stronger explanation of their ideological orientation than any of the primary formats or characteristics of those contests. 15

References Ansolabehere, Stephen. 2012. Cooperative Congressional Election Study, 2010: Common Content. [Computer File] Release 2: August 10, 2012. Cambridge, MA: Harvard University [producer] http://cces.gov.harvard.edu. Berdahl, Clarence A. 1942. Party Membership in the United States, I. American Political Science Review 36: 16-50. Burden, Barry C., and Steven Greene. 2000. Party Attachments and State Election Laws. Political Research Quarterly 53: 63-76. Campbell, Angus, Philip E. Converse, Warren E. Miller, and Donald E. Stokes. 1960. The American Voter. New York: John Wiley & Sons. Chen, Kong-Pin, and Sheng-Zhang Yang. 2002. Strategic Voting in Open Primaries. Public Choice 112: 1-30. Congressional and Presidential Primaries: Open, Closed, Semi-Closed, and Top Two. FairVote, May 2012. http://www.fairvote.org/research-and-analysis/presidential-elections/congressional-andpresidential-primaries-open-closed-semi-closed-and-top-two/, accessed May 5, 2014. Holbrook, Thomas M. and Raymond J. La Raja. 2008. Parties and Elections. In Politics in the American States: A Comparative Analysis, 9 th edition, ed., Virginia Gray and Russell L. Hanson. Washington, D.C.: CQ Press, pp. 61-97. Jacobson, Gary C. 2012. The Electoral Origins of Polarized Politics: Evidence from the 2010 Cooperative Congressional Election Study. American Behavioral Scientist 56: 1612-30. Kanthak, Kristin, and Rebecca Morton. 2001. The Effects of Electoral Rules on Congressional Primaries. In Congressional Primaries and the Politics of Representation, ed., Peter F. Galderisi, Marni Ezra, and Michael Lyons. Lanham, MD: Rowman & Littlefield, pp. 116-131. Kiely, Kathy. 2010. Voter Turnouts for Primaries A Concern. USA Today, March 26. http://usatoday30.usatoday.com/news/washington/2010-03-14-turnout_n.htm?csp=34, accessed February 28, 2014. Laakso, M and R. Taagepera. 1979. Effective Number of Parties: A Measure with Application to West Europe. Comparative Political Studies 12: 3-27. McDonald, Michael. 2012. 2010 General Election Turnout Rates. United States Elections Project, http://elections.gmu.edu/turnout_2010g.html, accessed April 21, 2014. Merriam, Charles Edward, and Louise Overacker. 1928. Primary Elections. Chicago: University of Chicago Press. New York State Voter Registration Form. 2014. http://www.elections.ny.gov/nysboe/download/voting/voteform.pdf, accessed May 8, 2014. New Hampshire Secretary of State. 2014. Voter Registration. http://sos.nh.gov/voterregfaq.aspx, access May 8, 2014. Norrander, Barbara. 1986. "Measuring Primary Turnout in Aggregate Analysis." Political Behavior 8 (4): 356-73. Norrander, Barbara. 1989. Explaining Cross-State Variation in independent Identification. American Journal of Political Science 33: 516-36. Norrander, Barbara. 2003. The Intraparty Gender Gap: Differences between Male and Female Voters in the 1980-2000 Presidential Primaries. PS: Political Science and Politics 36: 181-86. Norrander, Barbara, Kerri Stephens and Jay L. Wendland. 2013. Primary Type, Polarization of State Electorates and the Ideological Composition of Primary Electorates. Paper presented at the Midwest Political Science Association Conference, April 11 14, 2013. 16

Sides, John and Lynn Vavreck. 2013. On the Representativeness of Primary Elections. Paper presented at the conference on Political Representation: Fifty Years after Miller and Stokes, Vanderbilt University, March 1-2, 2013. Siegel, Mark A. 2011. Playing to the Fringes. Washington Post, September 4, 2011. http://www.washingtonpost.com/opinions/how-closed-primaries-further-polarize-ourpolitics/2011/09/02/giqarbpb2j_story.html, accessed February 28, 2014. Springer, Jennifer. 2012. South Dakota Voter Registration Down. Ballotpedia, August 14, 2012. http://ballotpedia.org/south_dakota_voter_registration_down, accessed May 5, 2014. 17

Table 1: Mean Ideological Difference Between Primary Voters and Their State s General Election Median Voter by Primary Type Voters in Democratic Primaries Closed Semi-Closed Semi-Open Open Mean Ideology -.66 -.73 -.76 -.86 Number of cases 2,075 1,843 1,492 511 Sign. of F-tests Compared to Closed.04.01.00 Compared to Semi-Closed.47.01 Compared to Semi-Open.05 Voters in Republican Primaries Mean Ideology.77.72.61.66 Number of cases 2,220 2,367 2,659 630 Sign. of F-tests Compared to Closed.10.00.00 Compared to Semi-Closed.00.12 Compared to Semi-Open.25 Source: 2010 Cooperative Congressional Election Survey 18

Table 2: Explaining Deviations from State s Median Voter by Primary Voters in Democratic and Republican Primaries in 2010 Voters in Democratic Primaries Voters in Republican Primaries State-Level Model Plus Individual Traits State-Level Model Plus Individual Traits Plus Tea Party Support Semi-Closed Primary -.09* (.04) -.06* (.03).02 (.03).04 (.03).04 (.03) Semi-Open Primary -.05 (.06) -.14** (.05) -.08 (.04) -.04 (.04) -.06 (.04) Open Primary -.15* (.07) -.18** (.06).05 (.05).15** (.05).14* (.05) Competitiveness- Governor Race -.03 (.02) -.01 (.01).01 (.01) -.00 (.01) -.005 (.01) Competitiveness- Senate Race.02 (.03).01 (.02).03 (.02).03 (.02).03 (.01) No Senate or Governor Race.12 (.12).02 (.05) -.21** (.07) -.23* (.09) -.21** (.07) Primary Turnout.74* (.35).26 (.19) -.99** (.30) -.59* (.24) -.34 (.23) Majority Party Status 1.32** (.35) 1.64** (.27) -1.18** (.19) -1.41** (.15) -1.35** (.17) Independent Lean Toward.22** (.03) -.13** (.02) -.17** (.02) Party Other Independents 1.03** (.05) -.73** (.05) -.44** (.04) Other Party s Partisan 1.36** (.07) -1.64** (.07) -.93** (.07) Female -.04 (.02) -.14** (.02) -.12** (.01) White -.16** (.04) -.04 (.04) -.02 (.03) Education -.09** (.01).01 (.01).01 (.01) Age.01** (.00).004** (.001).00 (.00) Born Again.34** (.03).21** (.02).18** (.02) Tea Party Support.27** (.01) Constant -1.52** (.23) -1.63** (.18) 1.42** (.12) 1.35** (.12).24 (.13) R 2.02**.29**.03.22.35 Weighted N 5,922 5,879 7,875 7,838 7,389 Source: 2010 Cooperative Congressional Election Survey Notes: Model is ordinary least squares regression with clustering by state. Entries in cells are regression coefficients, with robust standard errors inside parentheses. * = p.05; ** = p.01. 19

Table 3: Partisanship of Voters in Democratic and Republican Primaries in 2010, in percentages Voter Party Identification Democratic Primary Voters Four Categories Seven Categories All Types Closed Primary Semi-Closed Primary Semi-Open Primary Open Primary Own Strong 76 57 81 59 77 58 72 54 67 53 Partisans Weak 19 22 20 17 15 Independent Lean 12 12 9 9 12 12 14 14 22 22 Lean to Party All other Pure 8 5 7 3 9 5 11 7 8 7 independents Lean 4 4 4 4 1 Opposite Weak 3 1 3 1 2 1 4 2 3 2 Party Partisans Strong 1 2 1 2 2 Republican Primary Voters Own Strong 66 47 76 53 68 49 59 43 50 39 Partisans Weak 18 23 19 15 12 Independent 24 24 18 18 23 23 30 30 31 31 Lean to Party All other Pure 8 6 5 4 8 6 10 8 15 11 independents Lean 2 1 3 2 4 Opposite Party Partisans Weak 2 1 1.3 2 1 2 1 4 2 Strong 1.3.5 1 2 Source: 2010 Cooperative Congressional Election Survey Notes: The number of weighted cases for Democratic primary voters is 6, 198, F = 4.25, and significance =.00. The number of weighted cases for Republican primary voters is 8,033, F = 8.60, and significance =.00. 20

Figure 1a: Hypothetical Distribution of Ideology and Party with No Effect for Primary Type Very Conservative Republican Independent Moderate Democrat Very Liberal Figure 1b: Hypothetical Distribution of Ideology and Party with Primary Type that Encourages Partisanship over Independence. Republican Indep. Democrat Very Conservative Moderate Very Liberal Figure 1c: Hypothetical Distribution of Ideology and Party with Primary Type that Encourages Independence over Partisanship. Republican Very Conservative Independent Moderate Democrat Very Liberal 21

Appendix A: Classification of Primary Type by States and Parties, 2010 Closed Semi-Closed Semi-Open Open Connecticut Delaware Florida Kentucky Maryland Nevada New Mexico New York Oklahoma Oregon Pennsylvania South Dakota Rep. Utah - Rep. Alaska - Rep. Arizona California Colorado Iowa Kansas Maine Massachusetts Nebraska New Hampshire New Jersey North Carolina Rhode Island South Dakota - Dem. West Virginia Wyoming Alabama Arkansas Georgia Illinois Indiana Mississippi Missouri Ohio South Carolina Tennessee Texas Alaska - Dem. Hawaii Idaho Michigan Minnesota Montana North Dakota Utah-Dem. Vermont Wisconsin Louisiana and Washington State are excluded because of their nonpartisan primaries. Virginia is excluded because no validated votes in CCES. The Alaska Democratic Party shared a blanket primary with Alaska Independence Party and Libertarian Party. Since the Alaska Democratic Party s candidates received the bulk of the primary votes, we have classified it as an open primary. In 2010, the South Dakota Democratic Party allowed independents to vote in its primary (Springer 2012). Utah law allows the political parties to choose the format for their primaries (FairVote 2012). 22