Supranational Integration, Polarization, and Party-System Fragmentation

• In Event: Models of Electoral Competition

Abstract

I develop a model of multi-party electoral competition, where policy platforms are two-dimensional (consisting of continuous ideological position and a dichotomous position in favor or against membership in an international union that imposes binding policy constraint on the traditional left-right dimension). I distinguish between electoral (unconstrained) and parliamentary (constrained) platforms and assume that parties consist of two factions, the Opportunists (office-seekers) that seek to maximize vote (and hence seat) share and the Militants (ideologues) that seek to maximize their constituents’ expected utility. I then apply the equilibrium concepts of Coalition-Proof and Strong Nash equilibria to characterize a manifold of equilibria, ranging from moderate pro-membership, to populist, to polarized anti-membership ones for different configurations of the international union’s input (scope of policy constraints imposed) and output legitimacy (popularity). Finally, I apply the Nash bargaining solution---by allowing for the possibility of party splits as disagreement outcomes---in order to refine my equilibrium predictions and infer under what conditions party splits are the more likely outcomes depending on the perceived benefits of union membership and the scope of policy constrains that come with it. I show how populism can arise as the outcome of intra-party bargaining that keeps the party together in the face of strong factionalism over supranational integration. The model also predicts that party fragmentation (as a result of party splits) and ideological polarization is more likely when the orthogonal benefits of integration are lower and the scope of policy constraints is narrower.

Author

• Nikitas Konstantinidis, IE University