The refusal of Republican members of Congress to back their party's 2016 nominee became a defining story. This paper examines the reasons behind this movement by analyzing diverse explanations from media and categorizing them into four theoretical frameworks—policy preferences, identity politics, electoral calculations, and establishment interests. We then test these claims using empirical evidence.

Our findings suggest that members' religious backgrounds and gender identity were more influential than previously thought. These factors align with identity-centric perspectives often overlooked in political discourse.

We also reveal a counterintuitive pattern: career politicians from established institutions showed greater likelihood of supporting Trump, challenging assumptions about party loyalty. This discovery underscores the limited explanatory power of conventional wisdom regarding congressional behavior.