Political parties commonly experience internal disagreements. Recently, evidence is accumulating that outright internal discord makes a party much less attractive to voters. However, we do not understand well when citizens perceive a party to be internally conflicted in the first place. We here explain citizens’ perceptions from a democratic life cycle perspective: Factors related to the periodic conduct of elections induce higher levels of intra-party conflict and make it more visible to citizens. To test this argument, we combine survey data on citizens’ perceptions of political parties in Germany spanning 16 years with indicators moderating (the visibility of) intra-party conflict. The analysis shows that citizens perceive more internal conflict when parties are heterogenous, when they are governing, when election day is distant, and when electoral losses accumulate. This demonstrates the recurring patterns in citizens’ perceptions of political parties and suggests self-reinforcing dynamics between citizen assessments and election outcomes.

In the literature on the determinants of party unity, one pathway has remained largely neglected: division of labour. Given their workload, members of parliament (MPs) are only thoroughly concerned with a subset of policies. We argue that this results in MPs casting fewer dissenting votes on matters within their area of specialization since they have had the opportunity to shape the party line there. Regression analyses using data for the German Bundestag support this hypothesis, including four important refinements: Not only the current but also past membership in the responsible committee reduces an MP’s defection probability. Additionally, this pattern is more pronounced for policy spokespersons and for less consequential, i.e., non-legislative votes as well as for issues less salient to the MP’s party. The results have implications for our understanding of MPs’ legislative behaviour, the functioning of parliaments as institutions and for the relationship between parties, MPs and voters.

Observational studies and anecdotal evidence suggest that party unity improves a party's electoral performance. Yet, due to a lack of experimental evidence, the causal standing of these findings remains unclear. Moreover, party unity manifests in various ways and we do not know how much different types of party unity affect the vote. Relying on a conjoint experiment implemented in a probability-based survey of the German population, our study unveils the distinct causal effect of different forms of party unity on vote choice. We further establish that appearing united can compensate for substantive policy distances between parties and voters. These findings have important implications for our understanding of how citizens vote and how intra-party politics affects the political representation of citizens in democracies.

This article proposes a novel theoretical framework to account for the combined effects of regime type and patterns of executive authority on legislative party unity. We argue that broad presidential legislative powers favour coordination between the president and legislative parties under pure presidentialism, whereas under semi-presidentialism, strong presidents increase the potential for intra-executive conflict, submitting parties to cross-cutting pressures. We expect higher levels of legislative authority to increase party unity under presidentialism but decrease under semi-presidentialism. Moreover, when presidents are endowed with limited legislative authority, semi-presidentialism produces higher levels of party unity than presidentialism, but for sufficiently high levels of legislative authority there should be no difference across regime types. Our analyses of 1,586 pooled observations for 72 democracies from all regions of the world using the V-Dem measure of party cohesion demonstrate that presidential legislative authority, in combination with regime type, is indeed a key predictor of party unity.

It is common wisdom that the increase in the number of women in parliament brought along a new diversity of perspectives presented in legislatures. So far, however, we know little about the implications of women's presence on party cohesion. Moving towards a more complete understanding of how women affect political processes, this article addresses the question, does gender affect vote defection from party lines, and if so, under what circumstances? We argue that the actual and perceived risk associated with vote defection in roll-call votes is gendered and that this is constraining the leeway of women to rebel. Analysing roll-call vote data of the German Bundestag (1953–2013) provided by Bergmann et al. (2018), we show that gender exerts a consistent effect only if electoral safety and policy content are considered: it is in feminine policy areas and at high levels of electoral security that women are more likely than men to rebel. This finding implies that taking different incentive structures into account is key if we want to understand gendered legislative behaviour.

The existing comparative literature focuses on political institutions to explain party unity in parliament, and largely ignores the role of party characteristics in this process. This study argues that the strength of political party organization directly and independently influences the level of party unity. Organizational strength makes the party a valuable asset to individual legislators, thus increasing their willingness to be disciplined. Therefore, parties with strong organizations are likely to be more unified in parliament than those with weak organizations. I find support for this argument with data from four post-communist democracies: the Czech Republic, Estonia, Hungary, and Poland. Narratives suggest that the proposed causal mechanism is plausible.

Political parties are often faced with seemingly opposing goals when trying to secure members’ reelection and maintain party unity. On one hand, a party needs to fulfill members’ diverse electoral needs for their reelection, and on the other hand, the party must force members to vote in unison according to party lines for collective decisions. How does a party influence its members to take unified action while meeting their individual electoral needs? Through an analysis of the Japanese Diet, this study argues that parties attempt to achieve the reelection of their members and maintain party unity by manipulating legislative committee assignments and deliberations. In particular, the study demonstrates that a party shapes committees in a different way according to policy areas over which committees have jurisdiction. A party tends to accept its members’ requests for affiliation and allow their self-management in committees concerned with particularistic benefits so that they can deliver specific benefits to each electoral district. In addition, a party tends to assign members who have average policy positions in the party to committees concerned with general benefits to make policies that satisfy many constituencies.