A Trump-endorsed challenger beat incumbent Thomas Massie in a Kentucky primary on Tuesday, the latest victory in the 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.