Rep. Thomas Massie, the libertarian-leaning Republican congressman from Kentucky, is confronting a serious primary challenge on Tuesday as President Trump has thrown his full political weight behind efforts to unseat him. Trump has publicly urged Kentucky voters to "vote the bum out," marking one of the more aggressive intraparty fights of the 2026 primary season.

The race has attracted substantial outside spending, with billionaire donors aligned with Trump's political operation funding opposition to Massie. The congressman, known for his frequent breaks with party leadership and his votes against key Republican priorities, has long been a thorn in the side of the House GOP majority.

Massie's clashes with Trump date back several years, including his opposition to major spending and legislative packages. His willingness to vote against Republican leadership on procedural and substantive measures has made him a target for those who view party discipline as essential to governing effectively.

The primary is being watched closely as a test of Trump's continued influence over Republican primaries heading into the 2026 midterm elections. A Massie defeat would signal that Trump retains strong sway over GOP base voters even in races involving long-serving incumbents with devoted local followings.