Rhetoric and public policy scholars have shown interest in uncertainty and polysemy in Congress, but they have traditionally treated legislation as a given. Members of Congress disagree about what policy should be, but they also disagree about what any given bill proposes to do. From a rhetorical perspective, I investigate the creation of uncertainty about legislation through the 2013 Senate debate on immigration. I argue that legislation is inherently ambiguous because legislative debate is consistently pushed behind the language of statutes. Rather than consider statutes unto themselves, members of Congress understand them in terms of the potential acts they sanction. Legislation thus becomes a framework for action, and legislators work to construct the probable acts that will result from its passage. By conceptualizing legislation as a framework for action, I shed new light on an unexplored source of disagreement in policy debate.