Parties, preferences and influence in legislative decision-making

Political scientists have a long-standing interest in the acquisition and exercise of power in democratic institutions. Although considerable attention has been devoted to understanding the role of political parties in legislative decision-making, empirical studies relying upon observational data, such as roll call voting, have faced difficulty in disentangling the effects of party and preferences on legislative behavior This research uses new measures on individual roll rates of state legislators in the nonpartisan Nebraska legislature and a sample of partisan state legislatures to provide unambiguous evidence of causal effects of party influence in legislative decision-making. The results demonstrate that preferences provide the most consistent prediction of individuals’ roll rates.