When the partisan becomes personal: Mayoral Incumbency Effects in Buenos Aires, 1983–2019

A burgeoning literature finds that incumbency effects reflect mostly a personal rather than a partisan advantage. We attribute this to incumbents’ mobilization incentives. Incumbents have weaker incentives to exert costly effort on behalf of their copartisans in national races than in local ones, where their local power is at stake. We examine these implications in the Province of Buenos Aires, Argentina’s largest subnational unit, where midterm elections give mayors a strong incentive to help their copartisans running for the local council, but much weaker ones to support those running for a national seat. Using a regression discontinuity design, we find a large positive effect of incumbency in local mayoral and midterm elections. In contrast, local incumbents neither help nor hurt their copartisans running for the presidency or the national legislature.