Three Is a Crowd. Information and Electoral Coordination in Argentina

Successful coordination around a Duvergerian equilibrium requires accurate and consistent information about parties’ expected electoral support. In practice, such information is rarely available at the local level, where polls are prohibitively expensive, making voters’ coordination difficult. We leverage Argentina’s Open, Mandatory, and Simultaneous Primary Elections as a large-scale survey of voter preferences. Using data from 135 municipalities in the province of Buenos Aires during 2011-2023, we show that a narrower margin between the top two placed parties in the primary increases turnout and the proportion of positive votes, but decreases electoral fragmentation in the general election. Additionally, the second-placed one is substantially more likely to win the election than the third-placed one. In line with theoretical predictions, these phenomena are more pronounced (a) in concurrent elections; (b) in smaller municipalities; and (c) when the second-placed party is closer to the first-placed one.