Policy Bias Equivalence under Common Agency

This paper studies interest group influence on policy making. Lobbying occurs in a first price auction where an interest group wins with certainty, if her bid exceeds the loser’s bid by the policy maker’s valuation for the socially best policy. Otherwise the latter implements the privately known best policy. In equilibrium the size of the policy maker’s valuation does not matter for the size of the policy bias. The idea is to construct a “reference game” and to shift the support of the equilibrium mixed strategies into the original game, without altering the structure of the densities.