The Left Variance: How Electoral Mechanisms Shape Leftist Presidential Behavior in Latin America*

The emergence of left governments in Latin America is associated with voters’ dissatisfaction with neoliberal policy outcomes after democratic transitions. Although I believe this argument to be true, the explanations for why leftist governments behave differently are still incomplete. The main question this paper addresses is why some governments are social democratic whereas others are new-populist. I argue that presidents are molded into social democrats as a result of runoffs, and the presence of structured parties in legislatures. Given the need to convince the majority of voters to win the second round of an election, candidates are more likely to adopt moderate positions. Then, the likelihood of victory in a runoff is a function of candidates’ ability to make compromises and respect agreements in campaign and in office. This is especially observed when many institutional veto players compose the party system. I analyze a novel data set covering every Latin American presidential election since 1990. My results show support for the claim that the presence of strong parties in addition to runoffs encourages politicians to adopt responsible agendas, consequentially decreasing their chances of having new-