Companion Bills and Cross

The U.S. House and Senate were designed to have an adversarial relationship. Yet, House members and senators often collaborate on the introduction of “companion” bills. We develop a theory of these cross-chamber collaborations, which asserts that companion bill introductions are driven by legislators’ desire to increase the probability of bill passage and the relational difficulties in developing companion bill partnerships. To test the expectations emerging from our theory, we develop a novel data set of every companion bill introduction in the 111th and 112th U.S. Congress. Then, using social networking techniques, we develop an empirical model of partner selection in companion bill introduction. Our results are supportive of our expectations, and suggest that companion bills are more likely to survive chamber deliberation and are typically introduced by senior members with secure electoral margins