Since Donald Trump’s rise to the White House a decade ago, the United States president has purged his Republican Party of critics and rivals.

Many politicians dropped their earlier criticism of him and earned a place in his inner circle. Others never sought re-election or retired in the middle of their term to avoid a fight with the president, who is known for personal insults and lack of tolerance for dissent.

A few other legislators who chose to fight on were defeated by Trump-backed opponents in Republican primaries.

Congressman Thomas Massie, a Kentucky libertarian, is one of the last dissidents standing. He has been a rare Republican thorn in the side of Trump since the US president’s return to power last year.

Massie has voted against a key tax bill backed by the president, pushed for the release of government files related to late sex offender Jeffrey Epstein against the White House’s wishes and vocally opposed the war on Iran and US aid to Israel.

Now Massie is in a fight for his career as he faces a Trump-endorsed Republican opponent – Ed Gallrein, a former Navy SEAL officer – and an avalanche of pro-Israel spending in next week’s congressional primary in Kentucky.

The contest, however, goes beyond Trump and could be a litmus test for the faultlines emerging within the Republican base, including over military interventions and support for Israel.

For Massie’s supporters, the race on May 19 is a test for everything the congressman purports to stand for: unflinching loyalty to the US Constitution, political integrity and standing up to powerful special interest groups.

On Wednesday, influential right-wing commentator Mike Cernovich underscored another aspect of the contest in Kentucky – a showdown gauging the influence of podcasters who support Massie against campaign spending and traditional conservative media outlets.

“Massie’s primary is an interesting one to watch because it’ll show if podcasters and social media can drive out the vote in a material way. It’s unlimited money on the other end,” Cernovich wrote on X.

“If Massie loses, every Congress member will be cowed into fear. If he wins, it’s a new media era.”

Who is Massie?

So how did a 55-year-old House member come to represent a political movement at an inflection point in the modern history of US politics?

An engineer and inventor, Massie was born in a town in the Appalachian hills in West Virginia, near Kentucky and Ohio.

He attended Massachusetts Institute of Technology (MIT) and then went on to find a company that helped pioneer virtual reality technology and registered dozens of patents.

Massie married his high school sweetheart Rhonda, who died of an illness in 2024, with whom he had four children. The family moved to Kentucky in 2003, and Massie sold his firm to subsequently pursue a career in politics.

He became the judge-executive of Lewis County in 2011 and successfully ran for Congress a year later to represent Kentucky’s 4th District in the house of representatives, a Republican stronghold that encompasses rural areas as well as suburbs of Cincinnati, Ohio.

Massie quickly earned a reputation as a rebel, bucking the bipartisan orthodoxy on foreign policy as well as his own party’s consensus on many issues.

In the first vote of his full term, he joined 11 other Republicans to vote against the election of then-Speaker John Boehner and the only one to back his libertarian colleague Justin Amash to take the gavel.

Willingness to vote against his own party, did not earn Massie many friends on the Democratic side.

In 2021, Massie sparked a huge outcry from Democrats when he posted a Christmas photo of himself and his family members holding semi-automatic rifles at a time when gun violence was on the rise.

At times, his uncompromising stances have earned him near universal scorn. In 2022, Massie voted against a bill to make lynching – the extrajudicial execution of African Americans during racial segregation in the south of the US – a federal crime.

“This bill expands current federal ‘hate crime’ laws. A crime is a crime, and all victims deserve equal justice. Adding enhanced penalties for ‘hate’ tends to endanger other liberties such as freedom of speech,” he wrote in a social media post explaining his vote at that time.

“Lynching a person is already illegal in every state. Passing this legislation falsely implies that lynching someone does not already constitute criminal activity.”

Backing a largely symbolic vote against something as despicable as lynching, even if he opposed it, may have been the easier option.

The congressman has said that he has always had that rebellious streak.

“I was simultaneously the teacher’s pet and the teacher’s worst nightmare,” Massie recently told Mother Jones magazine.

“I would like to think I’ve become a lot more tactful, but I still won’t tolerate a wrong answer.”

Despite advocating for gun rights and small government, Massie has been able to team up with Democrats to push forward specific issues, especially opposition to military campaigns abroad.

Most recently, he became a leading figure in the effort to release the Epstein files, forging a strong partnership with Democratic Congressman Ro Khanna to pass a bill to compel the Justice Department to make the records public.

Israel and the race

Massie has also sided with Democrats in rejecting the war on Iran, and he has been one of the few Republican critics of unconditional US military aid to Israel.

Massie’s opponents – including pro-Israel groups and donors – are flooding the airwaves with ads against the congressman, often portraying him as not conservative enough and highlighting his vote against the tax bill.

One commercial that aired earlier this month featured deep fake, artificial intelligence-generated footage of Massie holding hands with progressive Democratic congresswomen Alexandria Ocasio-Cortez and Ilhan Omar.

The ad said Massie was caught in a “throuple” that is “worse than adultery” with the two female legislators.

It was released by a political action committee (PAC) called MAGA KY, whose top donor individual is Paul Singer, a billionaire investor who is also one of the top funders of the election arm of the American Israel Public Affairs Committee (AIPAC).

MAGA KY also received nearly $1m from another group called America 21 PAC, which is also funded by Singer, Federal Election Commission (FEC) records show.

On the Democratic side, dissent over Israel has been growing for years over human rights concerns as Palestinian rights advocates often embraced broader progressive causes.

But Massie has rooted his opposition to military assistance to the US ally in his broader opposition to foreign aid.

Since the outbreak of the genocidal war on Gaza, he has been more vocal about Israeli abuses, often questioning why US taxpayers are funding rights violations abroad.

In turn, pro-Israel groups and donors and funders have put Massie in their crosshairs.

Locked in a tight race with Gallrein, Massie has been emphasising what he describes as the malign role of pro-Israel lobby groups in US politics.

“There’s a foreign interest group called AIPAC that’s got the ear of the current speaker [Mike Johnson] and demanded 16 votes in April on Israel and the Middle East,” the congressman told conservative commentator Tucker Carlson earlier this month.

“We haven’t had 16 votes in April in the United States in Congress.”

Gallrein, Massie’s opponent, has leaned on his military service and Trump’s support to make his case to the voters.

“He sides with the radical Democrats in the liberal elites against us and our families again and again,” Gallrein said of Massie at a candidate forum earlier this month.

“President Trump knows this. Our party knows this, and you know this. That’s why President Trump asked me to serve again, and has given me his strongest endorsement in this campaign to join him and be your champion in Washington.”

But Massie has argued that the race is close not because of his opponent’s credentials or Trump’s endorsement but due to the millions of dollars in pro-Israel campaign money being spent to oust him from Congress.

In his interview with Carlson, he underscored that he overwhelmingly won his past two primaries despite being at odds with Trump.

“They’re position is more war. It’s more strife. It’s more bombs. It’s ‘send more foreign aid’. And those are the things I’ve been voting against,” he said, referring to pro-Israel lobby groups.

“So the real reason that this race is a real race and I may lose is because a foreign lobby has fully funded – to the extent that they have never done in a Republican race ever before – my opponent.”

Massie’s office and Gallrein’s campaign did not respond to Al Jazeera’s request for comment by time of publication.