Political equilibrium with private or / and public campaign finance : A comparison of institutions

We propose a theory of party competition (two parties, single-issue) where citizens acquire party membership by contributing money to a party, and where a member's influence on the policy taken by her party is proportional to her campaign contribution. The policy consists of informed and uninformed voters : only informed voters join parties, and the party campaign chest, the sum of its received contributions, is used to advertise and reach uninformed voters. Parties compete with each other strategically with respect to policy choice and advertising. We propose a definition of political equilibrium, in which party membership, citizen contributions, and parties' policies are simultaneously determined, for each of four financing institutions, running a gamut between a purely private, unconstrained system, to a public system in which all citizens have equal financial input. We compare the representation and welfare properties of these four institutions.