Domestic drivers of U.S. climate policyWhen Barack Obama became U.S. President in 2009, one of his main goals was to strengthen U.S. climate policy, but five years later this goal has still to be realized. Here, we explore the significance of this lack of achievement: First, we analyse the strategies of Democratic leaders in building winning coalitions in the U.S. Congress to overcome long-established conflicts concerning climate change policy in the United States. We find that it was close to impossible for the Senate leadership to come up with compromises that would mobilize sufficient support for climate legislation. Second, we investigate how three major events served to reinforce conflicts in the legislative climate debate: the establishment of the Tea Party movement, the oil disaster in the Gulf of Mexico and the financial crisis. Finally, we discuss implications of the Obama administration's failure to realize its climate policy ambitions in regard to prospects for U.S. participation in an international climate agreement. U.S. participation in international cooperation greatly depends on domestic policies. The deep conflicts in this issue area imply that U.S. participation in an international climate agreement in the near future is highly unlikely.