Thomas Massie, the Kentucky Republican congressman known as an MIT-trained engineer and libertarian, has become one of Trump's most vocal GOP critics. Despite voting with his party 91% of the time, Massie refuses unconditional loyalty to the president, earning him labels like "a complete and total disaster" from Trump and an endorsement of his primary challenger.

The conflict centers on trade, spending and executive power. Massie was one of only two House Republicans to vote against Trump's 2025 tax bill. He famously wears a homemade lapel pin displaying the national debt in real time and built his own Kentucky home using lumber he cut himself. "When I visit Monticello," he says, "I think about the things that Jefferson thought about."

The Epstein files transparency fight transformed Massie from an occasional irritant into a declared enemy. He partnered with Democrat Ro Khanna to force DOJ release of documents. With his primary against Trump-backed Ed Gallrein approaching, Massie remains defiant: "I'm glad I'm in his prayers," he replied after Trump called him a moron.