Intra-party dynamics in mixed-member electoral systems: How strategies of candidate selection impact parliamentary behaviour

Abstract

This paper contributes to our understanding of legislative behaviour in mixed-member electoral systems through a simple game-theoretic model. It argues that legislators seeking re-election in mixed-member electoral systems need to take into account the interests of two distinct selectorates rather than an electorate in order to maximize the probability of regaining a legislative mandate. Assuming that the policy interests of list and district selectorates systematically differ, legislators may face diverging demands from two principals whose relative capability to sanction incumbents crucially hinges upon the reward they may offer. Such reward, I argue, is best understood as the strength of the nomination, which refers to the probability of subsequent election. A simple game-theoretic model then shows how variation in the relative strength of both selectorates induces three different scenarios with distinct equilibrium outcomes and thus effectively impacts patterns of representation.