Party system erosion: Evidence from Peru

Weakly institutionalized party systems are a defining feature of third-wave democracies. Yet, in some countries like Peru, party weakness is not a static equilibrium but rather part of a dynamic process of “party system erosion” in which weak parties become weaker over time as independents come to dominate subnational posts. As I argue, party system erosion is driven by a particular configuration of institutional factors—weak party brands, ease of ballot access, and limited partisan control over resource distribution. These institutional features increase the likelihood that experienced candidates will run as independents. When these candidates are elected, they obtain more intergovernmental discretionary transfers, which are used to improve performance and maintain clientelistic networks. This resource advantage of independent officials further weakens party brands and reduces experienced candidates’ incentives to run with parties in future elections. I test this theory using a data set of 80,000 subnational officials and a regression discontinuity design.