Rep. Thomas Massie is staring down the biggest political threat of his 14-year congressional career on Tuesday as President Donald Trump and his allies unleash a political war chest in an effort to take out one of the last major Republican holdouts willing to publicly challenge him.

The showdown between Massie and Trump-backed retired Navy SEAL Ed Gallrein has turned into the most expensive House primary battle on record, with more than $32 million flooding into the race as both sides saturate northern Kentucky with attack ads, outside money, and even AI-generated deepfakes.

What was once a simmering feud has morphed into an all-out MAGA civil war.

Massie has spent years carving out a reputation as a libertarian-leaning conservative who often votes independently and sometimes infuriates Republican leadership. But his relationship with Trump deteriorated after repeated clashes over the administration’s handling of issues ranging from the release of government files connected to convicted sex offender Jeffrey Epstein to U.S. involvement in Iran and Trump’s signature domestic package, the “One Big Beautiful Bill.”

Trump eventually stopped hiding his frustration.

The president blasted Massie as the “worst Republican Congressman in history” before personally recruiting Gallrein to challenge him and putting the full force of his political operation behind the effort.

Now the question hanging over Kentucky is simple: Can even Thomas Massie survive a direct collision with Trump?

The spending numbers alone look staggering.

According to reporting from The New York Times, pro-Trump groups and organizations unhappy with Massie’s opposition to U.S. policy toward Iran spent heavily against the Kentucky congressman, including millions from groups tied to pro-Israel advocacy efforts. Meanwhile, Massie received support from outside groups and donors from across the political spectrum eager to keep one of Congress’s most unpredictable Republicans in office.

Massie has leaned into that dynamic as the campaign entered its final days.

“After months of beating around the bush, one reporter finally writes the true story of my race,” Massie said after reporting highlighted major outside spending against him.

The race has also veered into bizarre territory.

The New York Times reported that opposing groups unleashed deepfake advertisements depicting fake scenarios involving both candidates. One pro-Massie ad used AI-generated imagery portraying Gallrein abandoning Trump on a battlefield, while a pro-Gallrein advertisement depicted an AI-generated Massie socializing with progressive Democrats.

Then came perhaps the campaign’s biggest eyebrow-raiser.

Defense Secretary Pete Hegseth hit the campaign trail Monday to stump for Gallrein in a move that immediately drew criticism because Pentagon leaders traditionally avoid overt participation in partisan campaigns.

Hegseth, appearing at a Kentucky rally, described Gallrein as “reinforcements” for Trump’s agenda.

“I have to say up front, for the lawyers, that I’m here in my personal capacity as a private citizen,” Hegseth said.

Pentagon officials insist the appearance complied with ethics rules and federal law. But critics pointed out that a sitting Defense secretary jumping into a heated primary battle represents a rare break from long-standing Pentagon norms designed to protect the military’s image.

The Kentucky slugfest is also being watched for what it could reveal about Trump’s grip on the Republican Party.

Just days ago, Trump-backed forces scored another major win when Louisiana Sen. Bill Cassidy — one of Trump’s longtime GOP critics — lost his renomination battle. (RELATED: Former Senator Laments Anti-Trump Congressman’s Primary Loss)

Now Republican strategists are watching Kentucky, along with contests unfolding Tuesday in Georgia and Pennsylvania, for clues about whether Trump’s political muscle remains as powerful as ever.

For years, Massie built his brand around being the Republican who refused to fall in line.

Tuesday could determine whether that brand still works in Trump’s GOP.