Electoral competition and special interest politics

We study the competition between two political parties for seats in a legislature. The parties have fixed positions on some issues, but vary their positions on others in order to attract votes and campaign contributions. In this context, we examine whether special interest groups are governed by an electoral motive or an influence in their campaign giving, and how their contributions affect the equilibrium platforms. We show that each party is induced to behave as if it were maximizing a weighted sum of the aggregate welfares of informed voters and members of special interest groups. The party that is expected to win a majority of seats caters more to the special interests.