President Donald Trump scored a decisive victory against a Republican rival Tuesday, as Rep. Thomas Massie of Kentucky lost his primary to Ed Gallrein, a challenger the president endorsed after Massie became one of Trump’s most outspoken critics on Capitol Hill. The race drew record-breaking spending, making it the most expensive U.S. House primary in history, according to the Associated Press.

Massie, who has represented Kentucky’s 4th Congressional District since 2012, had built a reputation as a libertarian-leaning Republican willing to cross party leadership and the White House. He pushed for the release of documents related to Jeffrey Epstein, opposed the U.S. military engagement with Iran, and voted against Trump’s signature tax legislation last year. Those positions put him in direct conflict with Trump, who endorsed Gallrein and made Massie’s ouster a priority.

Gallrein, a businessman and political newcomer, campaigned on loyalty to Trump and aligned himself with the president’s policy agenda. The incumbent’s defeat cleared what had been one of the most persistent thorns in Trump’s side on Capitol Hill. Massie was among the few House Republicans who publicly broke with the president on multiple high-profile votes.

The loss leaves no doubt about Trump’s power to punish Republican defectors and reshape the party in his image ahead of the 2026 midterm elections.

MSI previously reported that Massie’s primary was part of a broader slate of Tuesday contests that tested Trump’s sway over GOP voters in races across Kentucky, Georgia, Alabama, and Pennsylvania. Read more.

Several other primaries Tuesday reinforced Trump’s influence. In Georgia, Secretary of State Brad Raffensperger — who drew Trump’s anger after the 2020 election — defeated a Trump-backed primary challenger, according to AP projections. In Alabama, former Rep. Barry Moore, who had Trump’s endorsement, won his GOP primary. In Pennsylvania, Democratic state Attorney General Josh Shapiro won his party’s gubernatorial primary unopposed, clearing a path to the general election.