Parties to an alliance: Ideology and the domestic politics of international institutionalization

While much research has been done on the domestic determinants of alliance institutionalization, there has been a neglect of the effect of domestic politics, by which we mean contestation between political actors in the same country. We hypothesize that the ideology of the parties governing countries negotiating the terms of security relationships will affect their preferences over the degree and kind of institutionalization seen in alliances. Drawing on previous literature, we argue that rightist parties are more sensitive to sovereignty costs and will therefore insist on maintaining more control over policy than their leftist counterparts. They can assert control either by imposing hierarchical forms of institutionalization when they are a stronger party to an alliance or by avoiding institutionalization altogether if they are the weaker party in an alliance. In contrast, we expect leftist parties to be less sensitive to sovereignty costs and generally favorable to more voice-driven, egalitarian institutions that have institutionalized mechanisms for consensus-building, regardless of their country’s relative power position. Combining the ATOP dataset on alliance design with the Parties Manifesto Project, we find broad support for our hypotheses. Our findings indicate that scholars should pay more attention to the internal ideological contestation within countries, making room for domestic political factors that go beyond regime type.