Interest Group Coalitions and Information Transmission

Though researchers of interest group behavior consistently note that groups often form coalitions when seeking to influence public policy, questions remain about when groups join forces and whether lobbying in a coalition is more or less effective than lobbying alone. In this paper, I approach these questions with a formal model of interest groups coalition formation among information-providing interest groups with non-identical preferences. I examine how the characteristics of groups and issues affect whether groups lobby alone or in coalitions and whether lobbying alone or lobbying in a coalition is most effective. Even when all groups desire the same policy, the uncertainty about other groups’ behavior can make lobbying too costly for some groups. When some groups want the policy more strongly than others, conditions that allow the most extreme groups to credibly transmit information can make lobbying too costly for more moderate groups. I show how coalitions can solve these problems and suggest that coalitions are more likely when there are multiple groups with similar, moderate ideologies, information is of low quality, and the cost of lobbying is high, relative to the benefit of the policy. I also show that coalitions make it more likely that the legislator chooses the groups’ preferred policy and that the legislator chooses the correct policy when groups can lobby in coalitions but cannot lobby alone. If groups can lobby alone or in a coalition, however, coalitions tend to make the legislator less likely to choose the groups’ preferred policy and to decrease the legislator’s welfare.