Congressman Thomas Massie, one of the most vocal critics of United States President Donald Trump, has lost his primary race to Trump-backed former Navy SEAL Ed Gallrein in a major political victory for the Republican leader. Massie had angered Trump by publicly opposing military action against Iran and sponsoring a bill that resulted in the release of files linked to convicted paedophile Jeffrey Epstein and resisting parts of the president's agenda. His defeat in the most expensive US House of Representatives primary race in history highlighted Trump's continued influence over the Republican Party and the political risks faced by Republicans who break with him.