Abstract

The sharp rise in partisan polarization in Congress has been one of the most prominent topics of academic debate for the past decade. In the 115th Congress, there is no ideological overlap between the two parties, and the distance between the Republican and Democratic parties is at a record high (McCarty, Poole, and Rosenthal 2006). One of the most commonly cited explanations for polarization is the primary election system. Senator Charles Schumer summarized this view in an editorial in the New York Times: “The partisan primary system, which favors ideologically pure candidates, has contributed to the election of more extreme officeholders and increased political polarization. It has become a menace to governing.” As Schumer and many others have suggested, primary voters are believed to pull candidates away from the center and warp the national balance of the electoral system. This argument has been so powerful that almost all who seek congressional reform advocate for changes to the primary system (i.e., Fiorina, Abrams, and Pope 2006; Mann and Ornstein 2012).