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ERLANGER, Kentucky—Bruce Spears voted for Ed Gallrein for one reason: “Because Trump told me to.”

The goateed retiree from Erlanger made clear that he had heard Gallrein speak (he was “better than I thought he would be”) and been growing skeptical of longtime incumbent Thomas Massie for a while. But the Kentucky Republican voter was a big admirer of Donald Trump (“he’s got balls”) and that was enough for him to switch from his support of Massie, whom he had backed in previous elections.

Gallrein is running to unseat Massie here in a Republican primary to represent Kentucky’s 4th District, but the challenger is basically an extension of the most powerful force in Republican politics: Trump’s endorsement. And rather than a race between candidates, the primary is mostly a referendum on Trump’s sway over the GOP today. With that question hanging over the ballot, the race has become the most expensive House primary in American history.

The race in northern Kentucky is hardly the only time Trump has targeted a disobedient Republican for replacement. It comes days after Sen. Bill Cassidy lost to a Trump-backed challenger in Louisiana, a half-decade delayed penance for the lawmaker’s 2021 vote to convict Trump after his post–Jan. 6 impeachment. And it comes weeks after Trump successfully ousted a handful of Indiana state senators who refused to accede to the president’s demand for a mid-decade redistricting.

But this race is different. Gallrein’s sheer anonymity makes him the ultimate test for power of Trump’s endorsement. The White House started a full-scale effort to recruit a primary challenger in the spring of 2025, long before the Epstein files had even become a major issue on Capitol Hill. None of their initial targets agreed to run. Eventually, they found Gallrein, a former Navy SEAL and failed state Senate candidate.

Gallrein has been a negligible presence on the campaign trail. His campaign signs feature his name, but in a font almost as large they remind voters he’s “endorsed by President Trump.” His website mostly contains b-roll for use by supportive super PACs. (Visitors to his page, before anything else, are also greeted by a pop-up that reminds them “Ed Gallrein Has Trump’s ‘Complete and Total Endorsement.’ ” When the candidate does appear, he emphasizes his support for Trump. Even when asked about the controversial conflict in Iran, he hails the president’s genius. In an interview with a local television station, the candidate described the president as “playing five-dimensional chess” in Iran and added that Trump is “resetting the entire global power structure.” Often, the only traces of a Gallrein appearance are posed photos shared afterward on his campaign Facebook page, the political equivalent of tears in the rain.

In almost any other matchup, Trump’s condemnation would basically doom the incumbent, particularly because the primary is tightly limited to registered Republicans. Kentucky has a closed primary, and independent voters had to change their registration by New Year’s Eve 2025 in order to participate. As one Republican strategist put it to Slate, “It’s obviously the most fascinating primary of the entire cycle: a sitting congressman with an independent brand going head-to-head with Trump.” The strategist noted that in almost any district, a sitting congressman targeted by the president would lose by 30 points.

But here, while Gallrein appears the favorite, the race is tight, and Massie is by no means out of it. Because although Trump has turned his ire on countless Republicans before, he’s never targeted any Republican quite like Thomas Massie. Then again, there is no Republican quite like Thomas Massie.

A congressional gadfly whose quirky libertarian politics sometime confound party lines, Massie has long been a burr under Trump’s saddle. Trump has railed at times against the Kentucky Republican going back to 2020, when Massie forced an in-person vote on an overwhelmingly popular COVID response bill at the start of the pandemic. Trump labeled him a “third-rate grandstander” and urged that he be “throw[n] out of the Republican Party.”

Since then, the relationship has ebbed and flowed. Trump even endorsed Massie’s reelection bid in 2022. However, it has gone downhill in Trump’s second term, starting with Massie’s refusal to back Mike Johnson in the speaker’s race (where Trump had to whip other recalcitrant members over the phone to finally get Johnson the gavel). Since then, Massie has repeatedly broken with Trump on other issues, including the president’s signature “One Big Beautiful Bill.”

One of the highest-profile rifts, however, is over the “Epstein files,” a catch-all phrase referring to information about convicted sex offender Jeffrey Epstein, who served as a conduit between powerful men and their victims. Massie has been one of the loudest House voices prodding the Trump administration to release more information on the sex offender and his accomplices. Last November, Massie, with the help of three other Republicans and every single Democrat, succeeded in pushing legislation demanding more disclosure, which was passed almost unanimously.

Epstein has been a sensitive topic for Trump. The president was at least friendly with the offender, and the full extent of their relationship was, at least before the Iran war, one of the most-discussed questions in all of American politics. And while Trumpworld’s disdain for Massie long predates the........

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