Donald Trump's presidency sparked intense debate over whether congressional Republicans were allies or adversaries. This article examines Trump's legislative backing from two angles. First, it forecasts his Republican support using historical data (1969–2016), finding levels consistent with expectations despite media skepticism.

Second, the piece explores factors influencing support versus opposition for their party's president. It reveals that conservative and establishment Republicans were more likely to back Trump, while female lawmakers and those from affluent, non-white districts opposed him more often.

The findings suggest significant tensions within the GOP based on ideology and identity. They also raise questions about potential realignment in American politics.