Abstract
The 2018 House of Representatives elections were a historic victory for the Democratic Party. As has been the case in past "wave" elections, however, this victory has posed the risk of factionalism within the party. In this paper we draw upon data on primary competition and independent spending to assess claims that Democratic primaries showed signs of emerging factional conflict within the party, and we compare Democratic primary competition to competition that emerged within the Republican Party during the early 2010s. We show that, despite arguments from progressive activists about reshaping the party, there was relatively little money spent in 2018 for primary challengers or for other primary candidates who ran against the party establishment. Most consequentially, the money that was spent came from groups with narrow issue concerns or with concerns about descriptive representation, not from insurgent ideological groups. Democrats, then, might develop a "primary problem" that resembles the one faced by Republicans in prior election cycles, but there is little evidence that the 2018 primaries were the beginning of such a development.