A GAME-THEORETIC MODEL OF PARTY AFFILIATION OF CANDIDATES AND OFFICE HOLDERS

In this paper, we develop a formal model of ambition theory, extending it to account for the choice of party affiliation. We begin by translating the expected utility, "calculus of candidacy" to the choice party affiliation. The model is then used to develop two game-theoretic models of affiliation. The first game models the affiliation decisions of an incumbent and a challenger within a single constituency. Our analysis shows these decisions to be fundamentally interdependent. Switches in affiliation can occur because of shifts in the electoral support for the parties, but also because politicians want to avoid contested primaries. Moving beyond one district, we show how the affiliation decisions of candidates running for different offices or in different districts are also interdependent. The analysis indicates that when electoral strength depends on who runs, politicians affiliated with a decaying political party are involved in a collective-action game.