These studies were discursive rather than explicitly theoretical, but the parallels between them and the contemporary work on game theory—a highly formalized and mathematical approach to explaining behavior—are unmistakable. The loose bargaining framework adopted by this research quickly proved a useful way to organize empirical research and produced many of the raw materials for a more comprehensive theory. The best-known studies of this early bureaucratic politics literature include Samuel Huntington’s The Common Defense (1961), Warner Schilling’s 1962 essay on the politics of national defense, and, most famously, Richard Neustadt’s Presidential Power (1960). Bureaucracies and executive branch officials were not portrayed here as neutral agents of implementation, but as active participants in determining the will of the state. These studies steadily built a case for a general theory of bureaucratic politics centered on bargaining games in the executive branch.