Lobbying together in a crowded, closing space: how democratic backsliding and population densities affect inter-organizational cooperation

Research on interest group cooperation and coalitions has largely focused on organizational characteristics and issue-specific incentives, leaving underexplored how broader environments shape inter-organizational relationships. This article examines how population dynamics and polity-level change jointly affect cooperation among interest groups. We argue that growing organizational density and democratic backsliding fundamentally alter the costs and benefits of coalition-building, producing both incentives for cooperation and pressures for differentiation. Empirically, we analyze survey data from 428 national-level interest groups operating in Czechia, Hungary, Poland, and Slovenia – four countries that combine dynamic organizational populations with varying degrees of democratic backsliding. Our findings show that perceived increases in organizational density strongly foster inter-organizational cooperation, whereas objective density measures do not. At the same time, closing political opportunity structures and political exclusion suppress policy-oriented cooperation rather than triggering compensatory coalition-building. Oppositional organizations cooperate more frequently overall, but their willingness to cooperate declines as perceived density increases, indicating a tipping point at which identity protection and competition outweigh collective action benefits. The article contributes to interest group and civil society research by linking population ecology and political opportunity structure perspectives and by showing that cooperation under democratic backsliding is contingent, non-linear, and context-dependent.