Coalition portfolios and interest group influence over the policy process

An interest group coalition exists whenever two or more interest groups collaborate in advocating their public policy agendas. Working together in coalition is one of the most common tactics that interest groups use to advance their interests in the policy process. The extant literature on coalitions emphasizes interest group decisions to participate or not in one coalition, or their strategy toward coalitions in general, but gives insufficient attention to interest group participation in multiple coalitions. To rectify this deficit, this article examines the implications of groups’ participation in multiple coalitions for their ability to influence the policy process. In order to account for interest group involvement in multiple coalitions, we introduce the concept of the coalition portfolio, which is the set of all coalitions within a given area of public policy in which an interest group participates at a particular point in time. The portfolio concept recognizes that interest groups may have a wide variety of coalition strategies depending on the mix of coalitions that they join. Variations in the structure of these portfolios matter both to interest groups and to policymakers. Moreover, coalition portfolios evolve over time as coalitions form and dissolve, and as political conditions adjust over the course of the policy process. We develop and test hypotheses that the change in the composition of coalition portfolios increases the influence of interest groups over public policy when: (i) the number of coalitions in a group’s portfolio gets larger; (ii) the average size of the coalitions in a group’s portfolio gets larger or smaller; and (iii) a group’s portfolio improves its position within the overall network of coalitions. Network position is measured based on the betweenness of interest groups in coalition networks, which gives higher scores to groups that lie on the shortest paths between other groups. We test these hypotheses while accounting for other explanations for interest group influence, including: (i) the group’s position in communication networks; (ii) the group’s number of registered lobbyists working on Medicare; (iii) whether or not the group has a Political Action Committee; (iv) the extent to which a group’s lobbying contacts lean toward one political party; (v) whether or not the group endorsed the legislation in question; (vi) the organization’s age in years; and (vii) whether the group is a citizens advocacy organization, a business advocacy organization or some other organizational type. We evaluate these hypotheses using a study of 115 interest groups involved in the enactment and implementation of the Medicare Modernization Act of 2003. This legislation established an outpatient prescription drug benefit in Medicare – a government health insurance program for the elderly and disabled in the United States – and made other significant changes to the program. We conducted personal interviews with representatives of 102 of these groups. We analyzed data resulting from these interviews using negative binomial and ordinary least squares regression models. The results support Hypothesis (iii); groups gain influence over the policy process when their coalition portfolios increase the extent to which they are situated between other groups in the coalition network. However, interest groups are limited in the extent to which they can create portfolios that have desirable levels of betweenness because network position is also a function of membership decisions made by all other groups in the network. These results provide insight into how the composition of coalition portfolios affects the ability of interest groups to exert influence over the policy process. This analysis is most directly applicable to policy debates over complex pieces of legislation.