President Donald Trump visited northern Kentucky this week. He held a rally in the Fourth Congressional District and endorsed a primary challenger to Congressman Thomas Massie. Trump’s visit drew national attention not only for his harsh remarks targeting Massie, but for the unusual step of campaigning against a sitting Republican member of Congress in his own state. Massie has long been known for his independent streak, frequently casting votes based on his reading of the U.S. Constitution—even when that places him at odds with party leadership or political allies. Massie’s approach has earned both criticism and respect in Washington and beyond—and has driven the President to run a primary opponent against him. The question remains on the impact of Trump’s endorsement in the May 19 primary.