Two-level game theory
The model views international negotiations between states as consisting of simultaneous negotiations at both the intra-national level (i.e. domestic) and the international level (i.e. between governments). Over domestic negotiations, the chief negotiator absorbs the concern of societal actors and builds coalitions with them; at the international level, the chief negotiator seeks an agreement that is amongst the possible 'wins' in his state's 'win-set'. Win-sets are the possible outcomes that are likely to be accepted by the domestic interest groups who either must ratify the agreement or provide some other form of government backing. International agreements occur when there is an overlap between the win-sets of the states involved in the international negotiations.