1 Introduction

The Master Lever is an option on a ballot to vote a “straight party” line—i.e., to select all candidates from a particular party in every race. The Master Lever reduces wait times and discourages roll-off.1 Between 1898–1980 it was offered in 30 U.S. states. Due to worries that it exacerbated uninformed voting and reduced accountability, however, the practice gradually fell out of favour.2 By 2018, it was available in just 9 states.

Although sometimes considered a marginal component of ballot design, the Master Lever does reduce positional voting and ballot non-completion. As a result, the political positions of candidates elected when the option is present are unlikely to perfectly mirror the political positions of candidates elected when it is not.

In this paper, we estimate the size and direction of this effect by exploiting post-WWII changes to U.S. states’ ballot design regulations. For our identification strategy, we use difference-in-differences to compare the Congressional voting records of senators in two types of states: leavers first had and then removed the Master Lever (15 states); stayers always offer the option (15 states). Prior to treatment, leaver and stayer states are relatively balanced on time-varying state-level observables; assuming state legislatures’ decisions to abandon the Master Lever do not partially correlate with a change in electoral preferences not picked up by these variables, our approach provides a causal estimate of the Master Lever’s impact on senatorial policy-making.

We find that more conservative senators are elected and incumbent senators vote more conservatively when the Master Lever is present; overall, this leads to a 3–6 percent rightward shift in their voting positions. Although senators immediately adjust to split-ticket voting once the option is removed, our evidence suggests that ballot design can nevertheless change the composition of a major democracy’s principle deliberative assembly.

Moreover, when we break the Master Lever effect down by party, we find it primarily driven by Republican senators. Republican positions shift 7 percent rightward when the Master Lever is present; for Democratic senators, however, there is no significant change.

In order to investigate precisely why the Master Lever affects each party differently, we construct a model of electoral competition. Intuitively, the Master Lever encourages partisanship voting. This gives candidates more room to secure financial and political support by catering to their parties’ agendas (party loyalty effect). It also shifts the average policy bliss point of remaining positional voters and so changes the platforms of the candidates they elect (swing voter effect). With or without the Master Lever, candidates adopt more extreme positions when both party loyalty and swing voter effects push rightward (Republicans) or leftward (Democrats). But when these conditions coexist with a straight-ticket voting option, then the latter pushes candidates even further toward extremes by: (i) reinforcing the likelihood of adopting (more extreme) party platforms; and (ii) reducing the influence of moderate (partisan) voters.3

To empirically determine the directional pull of the party loyalty effect, we assume each party’s bliss point corresponds to the median political position of its elected members in Congress and compare them to average state-level voter positions over the same period. We find both parties’ bliss points are consistently more extreme than average voter positions, suggesting a negative—i.e., leftward—party loyalty effect for Democratic senators and a positive—i.e., rightward—party loyalty effect for Republican senators.

Directly estimating the swing voter effect requires disaggregated data on individual voters’ partisanship and positions which we do not have. We can indirectly deduce it, however, within the framework of our model. Since the Democratic party’s party loyalty effect is negative but the Master Lever has not changed its senators’ positions, our model suggests partisan Democratic voters are more extreme than the average voter in senatorial elections—i.e., Democratic senators moderate their campaign platforms in order to attract non-partisan voters (positive swing voter effect).

For the Republican party, however, the party loyalty effect is positive and senatorial positions shift to the right when the Master Lever is present. According to our model, partisan Republican voters are therefore less extreme (and non-partisan voters more extreme) than the average voter—i.e., Republican senators appeal to swing voters on the right of their partisan base (positive swing voter effect).

Swing voter and party loyalty effects counterbalance each other for Democrats but push Republicans rightward. This dovetails with evidence suggesting Congressional polarisation is predominantly driven by the Republican party (McCarty, Poole, and Rosenthal 2006). It also emphasises that certain elements of ballot design may exacerbate differences in party ideology. We therefore join a large body of theoretical and empirical work investigating the U.S. political system’s increasingly polarised climate and the causal factors driving it—including income inequality (McCarty, Poole, and Rosenthal 2006; Garand 2010; Voorheis, McCarty, and Shor 2015), foreign competition and local labour market shocks (Autor et al. 2016), mass media (Campante and Hojman 2013; Prior 2013; Snyder and Strömberg 2010), gerrymandering (Engstrom 2013; McCarty, Poole, and Rosenthal 2009), electoral dynamics (Halberstam and Montagnes 2015), primary elections (Hirano et al. 2010; McGhee et al. 2014; Barber and McCarty 2015) and campaign contributions (Barber 2016).

We additionally contribute to a growing empirical literature studying how minor elements of ballot design affect voting behaviour (Heckelman 1995; Chen et al. 2014; Walker 1966). Evidence specific to the Master Lever suggests it decreases split ticket voting (Campbell 1980; Campbell and Miller 1957; Darcy and Schneider 1989; Kimball, Owens, and McLaughlin 2002; McAllister and Darcy 1992; Reynolds and McCormick 1986; Rusk 1970; Barnes, Tchintian, and Alles 2017), ballot non-completion (Feig 2007, 2009; Kimball, Owens, and McLaughlin 2002) and participation in non-partisan elections (Bonneau and Loepp 2014). Depending on the context, it can reduce or exacerbate voting errors (Herrnson, Hanmer, and Niemi 2012; Kimball and Kropf 2005). As we show in this paper, it also changes senators’ electoral incentives and has a non-negligible impact on their policy-making.

Although our results are derived from U.S. data, they speak to a broader question of possibility and ease of voting a straight ticket in an election. Thus, they contribute to the comparative analysis of electoral systems that vary in the salience and role of election candidates’ party affiliation. Figure 1.1 illustrates the range of electoral systems in the form of a spectrum: on one end, straight-ticket voting is mandatory—e.g., elections with closed party lists;4 on the other end, elections are between completely non-partisan candidates.5

Countries can move along the spectrum by changing the list proportional representation system (Kselman 2017; Buisseret and Prato 2018; Buisseret et al. 2019), adopting staggered calendars for local and national elections (Burki et al. 1999; Nickson 1995; Peterson 1997), as well as changing their districting and primary elections rules (see the literature cited above). Over its history, the U.S. gradually moved away from partisan elections—first, by introducing the Australian ballot at the turn of the twentieth century and then by removing the Master Lever in the years that followed. Since the Master Lever makes straight ticket voting easier, it boosts the importance of party affiliations in the electoral process. Removing it corresponds to the decrease in political parties’ influence and to decentralization.

Party-candidate association in elections

Note. Figure shows the availability and ease of voting a straight ticket in different electoral systems and the implied strength of association between parties and their candidates (from no association (left) to full association (right)).

Figure 1.1: Party-candidate association in elections

The rest of the paper is organized as follows. Sections 2 and 3 discuss our data and identification strategy, respectively. Empirical results are presented in Section 4. In Section 5, we develop a simple model of electoral competition to investigate the mechanisms driving those results. Section 6 concludes.

2 Data

To estimate the Master Lever’s contemporaneous impact on policy-making, we use data on U.S. senators elected (or appointed) to Congress between 1946–2009.6 In Appendix G, we compare our results to the period just after the introduction of the Australian ballot and up to the end of the second World War (1898–1945).

As we argue in Section 5, the Master Lever’s impact on policy-making is motivated by a desire to do well in future elections. As a consequence, it should primarily affect incumbent senators who intend to run for re-election. We nevertheless include in our sample even those senators who do not. First, U.S. senators are not subject to term limits and a very high percentage (79 percent) run for re-election at the end of their term (of which 82 percent are re-elected). Second, perceptions of electoral success predict whether an incumbent senator will run for re-election or not (see e.g., Moore and Hibbing 1992; Theriault 1998), suggesting that most retiring senators spend some portion of their time in office intending—or at least hoping—to run. Third, even when a senator genuinely wishes to retire from public office, the way he votes during his remaining tenure impacts the future electability of the candidate he (or his party) hopes will succeed him.7

To capture senators’ policy positions while in office, we use the first dimension of DW-NOMINATE, a multi-dimensional scaling application developed by Poole and Rosenthal (2015). DW-NOMINATE’s primary dimension assigns senators dynamic positional scores on the left-right spectrum based on their roll-call voting histories in Congress.8 Data on senators’ parties, (re-)election years and term lengths were obtained from the U.S. Senate website and the CQ Press Guide to U.S. Elections.

Data on our variable of interest—the presence of the Master Lever on state ballots—were hand-collected. To assemble it, we consulted states’ ballot design regulations in force during senatorial elections. We additionally cross-checked our interpretation of these regulations with data from Klarner (2010) and National Conference of State Legislatures (2019). Whenever possible, we also obtained images of ballots held in state archives and searched local newspapers for sample ballots printed before each election. We were able to determine the presence of a straight-ticket voting option for every mid-term and presidential election held in each state between 1898–2009.

The data we analyse in the body of this paper include 3,034 observations on 501 senators serving in the 31 Congresses held between 1946–2009. (See Appendix G for additional analyses using data from the period 1898–1945.) Every senator/election-cycle pair corresponds to three observations—one for each two-year Congress during a senator’s six-year term.9 The Master Lever was present for 1,415 senator-Congress observations; for 1,619 it was not.

In Section 5 we use the distribution of voters’ partisanship and positions within states to understand why the Master Lever impacts senators’ policy choices. To empirically proxy for the latter, we take the first dimension of Enns and Koch (2013)‘s dynamic scale of voters’ policy “moods.”10 Enns and Koch (2013)‘s indicator is a two-dimensional score that uses public opinion polls to gauge voters’ support for more (or less) government; as with DW-NOMINATE, explanatory power is principally concentrated in the measure’s first dimension.11

Table 2.1 displays observation counts broken down by whether the Master Lever was present on a senator’s upcoming election ballot. The first panel shows counts for red states (mostly Republican partisan voters), blue states (mostly Democrat partisan voters), purple states (equal and high numbers of Democrat and Republican partisan voters) and swing states (mostly non-partisan voters).12 The second panel breaks observation counts down by the political position of the average voter in a state: in right-wing states, the average voter is more conservative than the Republican party; in left-wing states, the average voter is more liberal than the Democratic party; in moderate states, the average voter’s position falls between each party’s position.13 Although partisanship is strong—particularly for the Democratic party—voters’ actual ideology appears far more moderate.

Table 2.1: Observation counts by constituent characteristics
Master Lever  
Absent Present   Total
State-level political affiliations  
  Blue 642 621   1263
  Purple 214 159   373
  Red 151 87   238
  Swing 402 260   662
State-level political positions  
  Left-wing 183 108   291
  Moderate 1226 1017   2243
  Right-wing 0 2   2
  Conservative 3 0   3
  Democrat 883 749   1632
  Independent 12 0   12
  Republican 721 666   1387

Note. Table displays observation counts by constituent characteristics, where each observation corresponds to a single senator-congress pair. Panel one breaks counts down by red states (mostly Republican partisan voters), blue states (mostly Democrat partisan voters), purple states (equal and high numbers of Democrat and Republican partisan voters) and swing states (mostly non-partisan voters). Panel two displays observations by positional classification. The final panel shows observation counts by party. (See Footnotes ?? and ?? for precise definitions of the categories listed in panels one, two and three, respectively.)

Table 2.1’s final panel tabulates observation counts by party. A higher number of Democratic senators were elected when the Master Lever was not on the ballot; where it was present, however, Democrats and Republicans were fairly evenly split. No Conservative or Independent senator serving in Congress between 1947–2009 was elected on a straight-ticket ballot.

The graphs in Figure 2.1 summarise the Master Lever’s presence and senator and voter characteristics across time. The number of states with a straight-ticket voting option on their ballots has steadily declined (top left-hand graph). Senate polarisation meanwhile has gradually increased (top right-hand graph). (Between 1947–2009 no state adopted the Master Lever.) Pre-1980s, Senate polarisation appears to have been driven by a left-ward shift from the Democratic party. Consistent with evidence from McCarty, Poole, and Rosenthal (2006), however, the post-1980 trend is especially pronounced in later years and is more likely caused by the Republican party.