Researchers analyze Portugal's local elections (278 municipalities) during a constitutional reform that introduced mayoral term limits. This change created an exogenous natural experiment testing incumbency status while keeping partisan affiliation fixed.
Data & Methods: Sixteen years of election data from 278 Portuguese municipalities provides the basis for analysis. The study employs innovative quasi-experimental approaches, combining regression discontinuity and difference-in-discontinuities designs to isolate effects.
Key Findings: These methods definitively separate personal incumbency advantage from partisan influence. Results show that the primary driver behind electoral success is the individual incumbent's own experience and resources—not their party affiliation—challenging conventional understandings of political representation.
Policy Implications: This nuanced understanding may reshape how analysts approach local governance, campaign finance regulation, and term limit debates in Portugal and other countries with similar political structures.
