Abstract: In this Article, we challenge the "monolithic view" of Congressional control over delegated power, which assumes that oversight committees will enforce the wishes of an enacting majority. In contrast with this prevailing view we argue that Congress consists of rivals who compete for control over power delegated to agencies. Individual committee members with access to oversight tools vie for control over agencies, both with each other and with past enacting majorities, to further their own interests. We argue, contrary to the conventional understanding, that committee members sometimes defy majority preferences rather than reinforce them. We claim that Congress creates an internal accountability problem when it delegates oversight power to its committees, just as it creates a problem of control when it delegates administrative power to agencies. Indeed, one delegation might exacerbate the other. And together, this "double delegation" creates a significant risk that agency decision making will be driven by the interests of small sub-majorities of Congress, and that this influence will subvert statutory commands. Playing off Bickel's famous characterization of the judiciary, we call this problem the "sub-majoritarian difficulty." Sub-majoritarianism may be so severe as to re-introduce parochialism into the implementation of federal statutes meant to impose national solutions - a phenomenon we call "backdoor federalism." We support our theoretical argument with an empirical test of decision making by the US Fish and Wildlife Service. In the literature on delegated power, our argument shifts the question from how best to make administrative agencies accountable to Congress, to who ought to be the principal, given the viability of multiple legislative principals. We speculate about how political scientists and legal scholars, respectively, might react to this competition among principals, and we explore measures that might minimize the adverse effects of sub-majoritarianism.