Today’s Republican Party is at a crossroads. The grassroots Tea Party movement that propelled it to electoral victories in 2010 has evolved into an increasingly public insurgency. In December, House Speaker John Boehner publicly denounced some of these Tea Party organizations, saying, “Frankly, I just think they’ve lost all credibility.” How will the political cleavages within the GOP impact the party’s electoral prospects and its policy priorities? In this issue, we explore these cleavages and their implications.