Policy-Seeking Parties in a Parliamentary Democracy with Proportional Representation: A Valence-Uncertainty Model

A unidimensional spatial model of multiparty parliamentary elections under proportional representation is presented, in which parties project that the median parliamentary party will implement its policy position. The parties are assumed to be uncertain about the electoral impact of valence issues relating to party elites’ images of competence, integrity and charisma. The assumptions of the model, highlighting the importance of the median party in parliament, are consistent with empirical work by McDonald and Budge. Under them, the existence of a Nash equilibrium under quite general concavity conditions is proved and it is shown that parties will moderate their positions when their valence images deteriorate. Computations of party equilibria are reported. The model and its implications for policy-seeking parties with results on vote-seeking parties can be contrasted with that recently reported by Schofield and Sened.