Different Campaigns, Similar Totals: Republican and Democratic Senate Candidates on Facebook in 2020

Facebook is often said to reward the American right. I test the claim on matched pairs: the Facebook pages of the Democratic and Republican nominees in 20 contested 2020 US Senate races, over the final eight weeks before 28 October 2020 (8,125 posts from CrowdTangle). Democrats posted about twice as often as their opponents (median 30 against 19 posts a week). Republican posts tended to draw more engagement each, especially shares and comments: within races, about 50% more of each, though how strong the evidence is depends on how posts and pages are weighted. Because Democrats posted more, total engagement did not differ clearly between the two sides, and per follower Democratic pages drew, if anything, more. The clearest differences were in kind. Democratic posts drew a higher share of "love" reactions in 17 of 20 races; Republican posts more "haha". Republicans posted more about Donald Trump, the Supreme Court and socialism; Democrats about health care, voting and donations. Angry reactions rose on posts mentioning the other side's presidential candidate. A candidate's share of engagement was not associated with their vote once the state's presidential vote was taken into account. On candidates' own pages, the two parties ran different campaigns and drew different reactions, but similar totals. The deposit includes page-level aggregates for each candidate and a race-level table. Post texts are not shared. Provenance and AI use. The data were exported from CrowdTangle in October 2020 for my doctoral research. This paper builds on my doctoral thesis (Hotham 2021, University of Bath). The analysis and writing were completed in 2026. The analysis code and drafts of the text were prepared with the assistance of an AI system (Claude, by Anthropic), which was also used to review drafts. I checked the analysis and the text and take responsibility for both. This version adds this statement to the paper; the findings are unchanged.