Resources, Enforcement and Party Discipline under Candidate-Centered PR

Abstract

When do candidate-centered electoral systems produce undisciplined parties? In this paper we examine party discipline under open list proportional representation, a system associated with MPs cultivating personal constituencies. We present a model explaining how legislators' preferences and support among voters mediate political leaders' ability to enforce discipline. We show that, conditional on MP preferences, disloyalty in candidate-centered systems depends on parties' organizational costs and resources for enforcing discipline. To test the model's implications, we use data on legislative voting in Poland's parliament since 1997. Our empirical findings confirm that disloyalty is conditioned on party leaders' enforcement capacity, MP preferences and party resources. We find that individuals with greater electoral contributions to the party in terms of votes are more disloyal, but only in the context of divergent legislator preferences. We also show that overall unity varies with changes in government status. Our results suggest that the theoretical relationship between open lists and party disloyalty should be treated as conditional and highly dependent on the context of the party system.