Disentangling the Incumbent’s Advantage: New Estimates of Partisan and Candidate Separate Effects

Abstract This article estimates separate individual and partisan incumbencyeffects in Uruguay’s regional elections (1971–2020). It contributes tothe limited evidence on incumbency effects in developing countries andto the emerging Differences-in-Discontinuities (Diff-in-Disc)literature, which addresses endogeneity and disentangles candidatefrom party effects within the same institutional setting. Exploitingconstitutionally mandated term limits and strong electoralenforcement, we identify clean causal effects using close electionsunder open and closed races. Results show a large and statisticallysignificant individual incumbency effect of approximately 74%,alongside non-significant partisan effects. These findings suggestthat incumbency in Uruguay is primarily personal rather thanparty-based. The results contribute to debates on personalization ofpolitics, proportional representation, and institutional developmentin Latin America, highlighting how strong democratic institutions cancoexist with highly individualized electoral dynamics.