Polarization and Shared Attention among Influential Amplifiers of 2018 U.S. Primary Candidates

Abstract

The spread of information on Twitter/X hinges on a relatively small set of influential accounts that shape the narrative during political events. In this paper, we identify and describe the ecosystem of influencers in the ego networks of candidates from the 2018 U.S. primaries across a large set of governor, house, and senate races. The ecosystem includes both amplifying influencers, who share tweets by candidates, as well as accounts regularly promoted by these amplifiers, whom we label ecosystem influencers. We classify these accounts with respect to their partisanship and political role. We find asymmetry across the two major parties, with Democrats receiving more formal party support than Republicans, whose amplifiers skew more towards ‘activist’ accounts that feature relatively high levels of bot or bot-like behavior. We also find that nearly all amplifying influencers share tweets from candidates representing a single political party. However, there is substantial overlap in the ecosystem influencers that these amplifiers promote, which are often journalists and news organizations, with over 30% of them retweeted by amplifiers on both sides of the political spectrum. We thus find that shared attention exists across these partisan amplifiers – far more than their promotion of candidate messages suggests – and that media accounts serve a central bridging function.