Noncooperative foundations of bargaining power in committees and the Shapley-Shubik index

In this paper we explore the noncooperative foundations of the bargaining power that a voting rule gives to each member of a committee that bargains in search of consensus over a set of feasible agreements under a voting rule. Assuming complete information, we model a variety of bargaining protocols and investigate their stationary subgame perfect equilibria. We show how the Shapley-Shubik index and other power indices can be interpreted as measures of 'bargaining power' that appear in this light as limit cases.