Electoral reform and partisan dealignment in Indonesia

There is a vast literature on the effects of electoral institutions on party systems. Research on the relationship between electoral systems and the strength of partisan identities, however, is inconclusive, as existing work mostly focuses on individual-level factors. In this paper, we analyze the case of Indonesia to illustrate the links between electoral laws and patterns of mass partisanship. By exploiting variation over time (four electoral cycles), we show that deep-seated partisan affiliations weakened substantially with the introduction of open-list PR, a system that provides strong incentives to cultivate a personal vote. By analyzing variation across space (189 districts), we further document that partisan alignment has been more pronounced where personal voting is more prevalent. These findings suggest that electoral institutions are a powerful driver of partisan identities, and that the effect of institutional change at the national level may be contingent on local politics.