To moderate, or not to moderate: Strategic domain sharing by congressional campaigns

We test whether candidates move to the extremes before a primary but then return to the center for the general election to appeal to the different preferences of each electorate. Incumbents are now more vulnerable to primary challenges than ever as social media offers a viable pathway for fundraising and messaging for challengers, while homogeneity of districts has reduced general election competitiveness. To assess candidates’ ideological trajectories, we estimate the messaging ideology of 2020 congressional campaigns before and after their primaries using a homophily-based measure of domains shared on Twitter. This method provides temporally granular data to observe changes in communication within a single election campaign cycle. We find suggestive evidence that incumbents in safe seats moved towards the extreme before their primaries and back towards the center for the general election, but only when threatened by a well-funded primary challenge.