Identifying the Source of Incumbency Advantage Through a Constitutional Reform


Mariana Lopes da Fonseca

The advantage incumbents experience in electoral races is well-documented. Those economists who tried to credibly identify it have so far either emphasized the personal incumbency advantage with the officeholder as the driver for the electoral success or the partisan incumbency advantage which assesses the benefits that accrue to a candidate from running for the incumbent party.

Mariana Lopes da Fonseca’s study provides one of the first causal estimates of both the personal and the partisan effect that contribute to an incumbent’s advantage at the ballot box. Her approach relies on a natural experiment that keeps the incumbency status of the party constant but creates an exogenous variation in the incumbency status of the candidate – the introduction of mayoral term limits in Portugal – as well as on a combination of two quasi-experimental methods, the regression discontinuity and the difference-in-discontinuities design. The economist finds that positive returns accrue to the rerunning officeholder by virtue of his or her incumbent status independent of the incumbency status of the party. Even though it would be reasonable to assume that parties play a significant role in attracting and retaining votes, she finds no evidence of a partisan incumbency advantage. This result has implications for politics at large since under these circumstances parties have an incentive to renominate officeholders as well as to acquiesce to their demands. Electoral mechanisms such as term limits might be useful in this case to stimulate competition.

Veröffentlichung:   American Journal of Political Science, 2017, Vol. 61, No. 3, 657–670.