With an estimated 72 percent of the vote counted, Ed Gallrein led with 54.4 percent to Massie’s 45.6 percent.

US President Donald Trump has tightened his grip on the Republican Party as Kentucky voters ousted one of the few conservative lawmakers willing to openly challenge his authority.

Congressman Thomas Massie‘s defeat, which was predicted by US news networks, including NBC and CNN, about two hours after polls closed on Tuesday, marks another victory in Trump’s campaign to punish dissent within Republican ranks.

With an estimated 72 percent of the vote counted, former Navy SEAL Ed Gallrein led with 54.4 percent of the vote to Massie’s 45.6 percent.

The Associated Press news agency called the race for Gallrein, whose campaign was backed by Trump’s endorsement as well as millions of dollars from pro-Trump and pro-Israel political lobby groups.

The contest, widely described as the most expensive House of Representatives primary in US history, saw more than $32m spent on advertising and offered the latest evidence of Trump’s hold over Republicans. It followed the primary defeat on Saturday of another Trump critic, Senator Bill Cassidy of Louisiana, as well as losses for dissenting Republican state lawmakers in Indiana earlier this month.

“Massie got Trumped. Donald Trump is the sun and the moon and the stars in the Republican Party in Kentucky,” Kentucky-based Republican strategist TJ Litafik said.

A test of Trump’s influence

The Kentucky vote was closely watched as a test of whether Trump’s hold on Republican voters remained firm despite concerns over his war on Iran, growing inflation and declining personal approval ratings, and whether there was still space in the party for lawmakers willing to break with him.

Massie had angered Trump by opposing US military action in Iran and Venezuela, criticising aid to Israel, resisting parts of the president’s agenda, and backing efforts to release files related to the late sex offender Jeffrey Epstein.

The president spent months attacking Massie, a libertarian-leaning seven-term congressman, calling him a “moron”, a “nut job” and a “major sleazebag”.

“Dealing with him is just horrible. I don’t think he’s a Republican… He’s not a libertarian,” Trump told reporters after polls opened on Tuesday.

“Sometimes they say he’s really a Dumb-ocrat. He votes against us all the time,” Trump said, using a nickname he frequently deploys against Democrats.

‘I’m not running against President Trump’

In the northern Kentucky city of Covington, Rob Barkley, a former Trump supporter who backed Massie, said the president’s attacks had pushed him further towards the congressman.

“He’s on the Republican side, so he has a conservative mindset,” Barkley told US media after casting his ballot.

“But he’s not as far-right leaning as Trump’s politics,” he said.

Massie, who voted with Trump roughly 90 percent of the time during the president’s second term, framed the contest as a broader test of independence within the Republican Party.

“I’m not running against President Trump. Most of the people voting for me support President Trump like I do,” Massie said.

Secretary of Defense Pete Hegseth also made a rare appearance in Massie’s district on Monday to campaign for Gallrein.

Federal law restricts government employees from engaging in partisan political activity while on duty, but Hegseth’s office said he attended in a personal capacity and that no taxpayer money was used.

Trump later revealed that Hegseth’s campaign appearance came just hours before the US had expected to launch a new military assault on Iran, although the operation was later postponed.

Several US states, including Georgia and Pennsylvania, held primaries on Tuesday in advance of November’s midterm elections, but the Kentucky race emerged as one of the night’s most closely-watched contests.

Massie, first elected in 2012, had long been one of Trump’s most persistent Republican critics.