Sub-national sources of multipartism in parliamentary elections: Evidence from Korea

Acknowledging the importance of diverse political institutions in explaining party system fragmentation, this is the first attempt to extend the existing perspective on local elections to legislative elections under a 'single-member simple-plurality electoral system in a decentralized unitary context'. The importance of electoral competition patterns in local elections is assessed to determine electoral multipartism in a given district in legislative elections. The unit of analysis is thus the 'electoral district' in which a legislative election under an SMSP is basically held. With evidence from the Korean case, it is argued that 'local/district partisan characteristics' - different levels of partisan strength and subsequent partisan fragmentation - influence the degree of electoral multipartism in legislative elections across districts, while all other district-level factors are held constant. The findings suggest that we need to consider sub-national and sub-provincial local elections if we are to obtain a systematic understanding of electoral multipartism in legislative elections.