ideals or opportunity? an equilibrium model of party switching in parliamentary democracies

I develop an equilibrium model of party switching in parliamentary democracies. The politicians are heterogeneous in their ideologies, resources, and devotion to their ideologies. The political parties are also heterogeneous in their ideologies and resources. Accordingly, I propose two possible explanations for a politician’s party-switching decision. First, a politician may behave ideologically by switching to a party that matches better with his/her ideology. Second, a politician may behave opportunistically by switching to a party that provides more political power. The model also proposes an explanation for the existence of multiple parties in a given ideological category of the political spectrum. The larger parties have more club goods to offer to their members. However, a politician’s marginal productivity in producing party rents is decreasing in party size, and therefore a larger party offers less private goods to its new members. The sum of his/her private and club goods define a politician’s power in a party, and depending on which of its components dominate, s/he may obtain a greater power in either a large or a small party. As a result, in equilibrium there is one large party and several small parties in each category of the political spectrum. Finally, the model proposes an explanation for politicians who have high resources but prefer to join parties that have low chances of winning a seat in the parliament. The heterogeneity in politicians’ devotions to their ideology imply that these politicians derive a greater utility by being in a party with a high ideological match than being in a party that provides more political power. I will test this model with a data I constructed on Turkish politicians who gained a seat in the parliament between 1995-2014. The simulated maximum likelihood estimation will allow me to identify the relative importance ideology and power for a politician’s party choices. I will conduct policy analysis of increasing the party-switching cost, imposing ideological discipline within a party, and imposing term limits.