#NeverTrump: Why Republican members of Congress refused to support their party's nominee in the 2016 presidential election

In an election characterized by countless headlines, the refusal of Republicans to support their party's nominee was a constant topic of discussion in 2016. Our paper looks to explain why Republican members of Congress joined the so-called #NeverTrump movement. In the first part, we document the varied-and often contradictory-explanations of the #NeverTrump movement offered by journalists, pundits, and politicians during the campaign. We then categorize these popular explanations into four theoretical categories: policy preferences, identity, electoral motivations, and establishment dynamics. In the second part, we test the varied claims. We believe two findings stand out and have broader implications for American politics. First, despite the popular belief that members of Congress are single-minded in their pursuit of reelection, we found that a lawmaker's religion and sex-both in the identity category-had the largest effects on the decision to join the #NeverTrump movement. Second, the results show that establishment Republicans were more likely to support Donald Trump's candidacy. Notably, the direction of this effect is inconsistent with popular explanations of the #NeverTrump movement but consistent with a range of academic studies.