  We propose a game-theoretic model to investigate how non-superpowers with
heterogenous preferences and endowments shape the superpower competition for a
sphere of influence. Two superpowers play a Stackelberg game by providing club
goods. Their utility depends on non-superpowers who form coalitions to join a
club in the presence of externality. The coalition formation, which depends on
the characteristics of non-superpowers, influences the behavior of superpowers
and thus the size of their clubs. Our data-based simulations of the subgame
perfect equilbirum capture how the US-China competition depends on other
countries.
