Opposition Party Strategy and Spatial Competition in Dominant Party Regimes: A Theory and the Case of Mexico

This article provides a non-formal modification of the standard spatial model of party competition to make it more applicable to the study of opposition parties in dominant party systems in transition. Dominant parties' virtual monopoly over resources forces challengers to rely on activist-based strategies. Challengers then face the problem of balancing programmatically radical activists against the moderate preference of the median voter. The article shows that opposition parties' programmatic locations depend on the number of competing parties. Contrary to standard expectations, it finds that two-party competition between the incumbent and one challenger produces a center-fleeing strategy by the challenger, whereas three-party competition between the incumbent and two challengers yields center-seeking strategies by both challengers. The second half of the article applies this modified model to the case of Mexico. Data come from in-depth interviews, electoral returns, public opinion polls, and original sample surveys of national party leaders and activists.