A challenger endorsed by Donald Trump beat incumbent Thomas Massie in a Kentucky primary on Tuesday, the latest victory in the US president’s efforts to oust the remaining dissenting voices in his Republican Party.In the most expensive US House nomination battle ever, the 14-year congressman lost by 55 per cent to 45 per cent to military veteran Ed Gallrein, who was backed by Trump and some of his billionaire donors.Massie had been one of Trump’s most prominent Republican critics in Congress, clashing with the president over the Iran war, the Epstein files and the landmark “Big Beautiful” fiscal legislation.This week, Trump called him “the worst congressman in the history of our country”.Trump has ended the political careers of many Republican dissenters since his first election a decade ago. Last weekend, Louisiana senator Bill Cassidy also lost his Republican primary against a Trump-backed candidate, Julia Letlow. Thomas Massie gives his concession speech. Photograph: Jon Cherry/Getty Images The president on Tuesday endorsed Texas’s attorney-general, Ken Paxton, over John Cornyn, a senator for more than two decades. The president said Cornyn “was very late” to endorse him in the 2016 presidential campaign.In Kentucky, Gallrein, a political novice, was boosted by the American Israel Public Affairs Committee, the pro-Israel group, and the Republican Jewish Coalition.Gallrein was also supported by billionaire pro-Trump donors, including Paul Singer, John Paulson and Miriam Adelson, who gave millions to political action committees that opposed Massie.In total, Pacs spent more than $33 million on ads in Kentucky’s fourth district, which stretches from the suburbs of Louisville towards Cincinnati, Ohio, and to the north-east hills of Kentucky, where Massie lives, according to AdImpact.“It’s a referendum on Israel’s influence,” said Massie about his election in an interview with The Financial Times before the vote. “Can they buy a seat for a warm body in Kentucky?”Asked last week if he would consider running again if he lost, Massie said he would not speculate.Trump had made clear his determination to seek revenge against Massie. In a Truth Social video supporting Gallrein this week, the president said: “He is fantastic, but forget that . . . Massie is the worst congressman in the history of our country, always voting against Republicans and good values.”Massie has opposed the president’s war against Iran, criticising the high cost and national security rationale for the conflict as well as the president’s decision to take action without congressional approval.He also pushed for the release of files relating to late sex offender Jeffrey Epstein and voted against the multitrillion-dollar tax and spending legislation last year, known as the “One Big Beautiful Bill”, for massively raising US debt.Defence secretary Pete Hegseth on Monday campaigned in Kentucky to paint Massie as an obstructionist. “In the middle of a fight you don’t weaken your own side,” Hegseth said.But Kentuckians said the issue was less a clash over foreign affairs and more a personality contest between Massie and Trump. - Copyright The Financial Times Limited 2026[ Thomas Massie: The Republican who stood up to TrumpOpens in new window ][ Keith Duggan: Trump taunted from beyond the grave by Epstein filesOpens in new window ]