AbstractDonald Trump's rhetoric, character, actions, and policy agenda have regularly posed strategic dilemmas for congressional Republicans. While Trump and much of his agenda are broadly unpopular, he has continued to enjoy strong support from the Republican voters who form their core electoral support. In this article, we analyze congressional Republicans’ responses to several of Trump’s most widely reported and controversial actions and comments as well as his legislative agenda. We find that congressional Republicans' personal and legislative positions on Trump reflected their electoral circumstances, their prior reactions to Trump during the campaign, and their ideological leanings. We also consider the positions adopted by congressional Democrats, who faced a more conventional problem of adapting to the president’s level of local support.