In this dissertation project, I examine how elections produce the diverse preferences within political parties and how these differences are managed by party organizations in legislatures. Existing research on legislative parties suggests that electoral incentives shape legislative behavior and individual politicians delegate their power to parties in order to reconcile the pursuit of individual interests with collective needs. However, especially outside the US Congress, little is known about 1) sources of ideological heterogeneity within parties and 2) the sanction and reward mechanisms used for parties to overcome heterogeneity and achieve collective goals. In order to address these questions, this study investigates how patterns of candidate competition at the electoral district level affect the ideological cohesion of legislative parties and how party leadership allocates posts and resources to legislators. By focusing on contemporary party politics in Japan and the US, I clarify the logic of legislative parties under different circumstances, especially the difference between parliamentary lower houses and other chambers. These two countries have important common features: a two-party system operating entirely or mostly under plurality electoral systems. While an SMD-based electoral system in the lower chamber promotes a two-party system and usually single-party majorities, these parties face the challenge of how they maintain party discipline. These institutional characteristics enable us to engage in within-country comparisons with key features varying. In terms of methodology, I make use of scaling methods on survey data analysis in order to clarify how electoral competition shapes the pattern of intra-party politics and party leadership strategy on post and resource allocation within parties. This study also illuminates the possibilities for survey data analysis approach and cross-national analysis on the causes and the consequences of party ideological cohesion.
展开▼
