Institutions, parties and the evolution of electoral preferences

Political institutions and parties define the set of choices faced by voters, and structure the evolution of electoral preferences over the election cycle. While previous research examines the characteristics of institutions, here we consider the influence of political parties. We theorize ways in which they matter to the formation of electoral preferences over the election timeline, and also how these relate to institutional features. Our analysis simultaneously assesses the influence of different system‐ and party‐level variables on the dynamic structure of voters’ preferences in legislative elections using a dataset of 27,357 vote intention polls in 26 countries since 1942, covering 231 discrete electoral cycles and encompassing 208 political parties. The results indicate that electoral institutions and parties are both important, but the characteristics of parties matter most of all, and effectively mediate institutional influences. These results have implications for the effects of election campaigns, the prediction of election outcomes, and party behavior itself.