Influencing Connected Legislators

This paper studies how interest groups allocate campaign contributions when congressmen are connected by social ties. We establish conditions for the existence of a unique Nash equilibrium in pure strategies for the contribution game and characterize the associated allocation of the interest groups' moneys. While the allocations are generally complex functions of the environment (the voting function, the legislators' preferences, and the social network topology), they are simple, monotonically increasing functions of the respective legislators' Katz-Bonacich centralities. Using data on the 109th-113th Congresses and on congressmen's alumni connections, we estimate the model and find evidence supporting its predictions.