At Pee Wee’s Place, a bar and restaurant in Crescent Springs, northern Kentucky, biscuits and gravy go for $6 and liver and onions for $14.75. The walls are adorned with US flags, sports memorabilia, amusement machines, a TV showing Fox News and a poster that proclaims: “Let the gays get married. Let the rednecks have their guns. Let the atheists be atheists. Let the Christians be Christians. America is about FREEDOM.”

Sitting at the bar, John Johnson, 78, and his son Lance, 47, are discussing an upcoming election in which Thomas Massie, a maverick congressman, is aiming to prove that a Republican can defy Donald Trump and survive. “I’m leaning to Massie because I like his attitude when it comes to being straight up on issues,” says John, a contractor who voted for Trump in 2024. “Him and Trump beat off each other every now and then, but he’s a constitutionalist, he speaks his piece and he’s right a lot of times.”

Kentucky’s fourth congressional district wends its way from Louisville’s outer suburbs north towards the commuter fringes of Cincinnati, Ohio, and east to the edge of Appalachia. A Republican primary election here on 19 May will pit Massie against a Trump-endorsed challenger, Ed Gallrein, a farmer and retired US Navy Seal, in a crucial test of the president’s strength.

Massie, 55, is already the exception that proves the rule of Republican politics. While others have capitulated and genuflected to the president over the past decade, eliciting comparisons with a personality cult, the seven-term congressman with a libertarian bent has emerged as ever more defiant.

He voted against Trump’s sprawling tax and spending cuts bill; co-authored legislation compelling the justice department to release the Jeffrey Epstein files; sought to revoke tariffs on Canada; and joined Democrats in opposing Trump’s decisions to attack Venezuela and Iran without congressional approval. “Bombing a country on the other side of the globe won’t make the Epstein files go away,” Massie said.

Now Trump is gunning for revenge. He has branded Massie a “lowlife”, “moron” and “weak and pathetic”, and even mocked him for remarrying 16 months after the sudden death of his wife of more than 30 years. He told a rally in the district in March: “We’ve got to get rid of this loser. This guy is bad. He’s disloyal to the Republican party. He’s disloyal to the people of Kentucky, and most importantly, he is disloyal to the United States of America. And he’s got to be voted out of office as soon as possible.”

Two of the president’s most trusted strategists, Chris LaCivita and Tony Fabrizio, are leading Maga KY, a political action committee backing Gallrein’s bid to unseat Massie in what Politico has dubbed “the Beltway v the Bluegrass”.

The outcome is far from certain, with early polling suggesting a close race. One source in the state Republican party said: “Massie is in trouble,” pointing to his lack of presence in the district and weak ground game. Others contend that, with impressive fundraising and the advantage of incumbency, the congressman is well placed at a moment when approval for Trump is cratering because of the Iran war and rising gas prices.

The race has effectively become a stark referendum on the two men. Shane Noem, the chair of the Kenton county Republican party, said: “It’s a pick-a-side moment for a lot of members. Congressman Massie has been in office for 14 years and has been a consistent advocate for his platforms. President Trump’s been a known entity since 2016 in the Republican party. A lot of voters are wrestling with: are we with the president, or are we with our congressman?”

The district, with a population of 776,082, is 86% white and has a median household income of $81,874. Trump carried it with two-thirds of the vote in 2024; Massie won the past three primaries with three-quarters of the vote. For many loyal Republicans, the men’s feud has created an agonisingly personal choice.

Steven Doan, a state representative aligned with Kentucky’s “Liberty” movement, said: “It’s kind of like Mommy and Daddy fighting. You love both of them and you support both of them. But at the end of the day, Thomas has been our guy for a long time and there’s a lot of loyalty here in the district to him. People seem to appreciate that at least we have one honest politician in Washington DC.”

Doan gives short shrift to Gallrein. “Nobody knows anything about the guy, and he’s not even running a campaign. The president is essentially running the campaign on his behalf. He won’t debate; he won’t tell you where he stands on the issues; he’s basically taking the Joe Biden-in-the-basement strategy, and that’s what he’s trying to run with.”

Some voters admire Massie for his uncompromising principles and willingness to stand his ground against the president on difficult issues. Back at Pee Wee’s Place, Lance Johnson, who voted for Trump three times, reasoned: “I’ve coached football and, if every coach agrees with each other, then I think something’s wrong, so there has to be somebody that disagrees with something.

“Massie is 90% of the time with Trump. It’s just one or two things that he doesn’t, and I agree with him on those one or two things. I’d like to see the Epstein files come out completely. Everybody that is a part of it needs to be shown.”

In addition, Trump’s stock has fallen with some Kentuckians struggling with an affordability crisis. Lance added: “The Iran war could have been handled a lot better. We were walked into it. I drive every day for my work and equipment takes gas. I’ve got two young kids. Groceries have gone up, so it’s been tougher. Everybody is spending more money right now.”

But sitting at a table nearby, another patron was not so impressed by Massie’s stubborn streak of rebellion. Jim Carmichael, 57, who runs a property company, views Massie as a “Rino” (Republican in name only) who votes against the party line far too frequently.

“I don’t mind anybody calling things into question, but if you’re the dissenting vote in the party, or if you are the vote that lets the other party win, then I have a problem with it,” Carmichael said. “There were a few times in particular that Massie should have voted with the president, and he didn’t, and it had no effect. He was doing it just to make a point.

“Sometimes there’s a greater good, right? Your point’s been made, so why do it? It’s fine if he wants to stand on that principle, more power to him, because he’s going to find he’s without a seat.”

Danny Ridder, a retired educator, 74, shares the frustration. “Everything that is proposed to him, he votes against it,” said Ridder. “There’s gotta be reason, and he doesn’t share those reasons.”

This vicious contest is not taking place in a vacuum. Kentucky, the birthplace of former Republican president Abraham Lincoln, was also crucial to the early years of the Tea Party movement, which stirred populist resentment towards government spending, and attracted both conservatives and libertarians.

Senator Rand Paul of Kentucky, son of former congressman Ron Paul, was elected in 2010 with Tea Party backing and often adopts libertarian positions, including opposition to overseas military interventions. Massie gained his seat in 2012. Meanwhile Senator Mitch McConnell, once a personification of the Republican establishment, has himself shown an independent streak by bucking Trump in recent years.

Steve Voss, a political scientist at the University of Kentucky, noted that research has shown the fourth congressional district is the only part of Kentucky where people identify as midwestern, rather than southern. “When the Tea Party arose in roughly 2010, it was northern Kentucky, as with the rest of the midwest, where that movement was concentrated,” he said.

Massie plays up to the image of rugged individualism. In 2021, he was criticized after sharing a Christmas photo of his family posing with military-style rifles, just days after a deadly school shooting. His bio on the X social media platform describes him as an “Appalachian American” and “Engineer, Farmer, Inventor” with 30 patents.

Indeed, Massie lives in a self-built, 4,400-sq-ft timber frame home on a 1,000-acre farm in Lewis county, Kentucky. The house is entirely off-the-grid, powered by solar panels, and features a repurposed wrecked Tesla Model S battery and rainwater collection system. He calls it “the Shire”, a reference to the self-sufficient home of the hobbits in JRR Tolkien’s fantasy world. He plays banjo and does not own a TV.

He has been dogged in pursuit of the Epstein files, working across the aisle with Ro Khanna, a Democratic congressman from California. Khanna said: “He is principled, very courageous, brilliant mind, quick-witted, willing to take risk. I have a lot of respect for him. He has the entire Trump presidential campaign apparatus running against him in a congressional seat. He is showing incredible guts and, when he wins, he’s going to be an even bigger national figure.”

But Massie’s rigid ideological commitment could hurt him at the ballot box. Early in his career, Massie refused to help his constituents access federal programs that he opposed, a hardline stance that permanently alienated local business leaders and officials.

Tres Watson, a Republican political strategist and host of Kentucky Politics Weekly podcast, said: “It’s not entirely a Trump-Massie battle. There’s probably 30% of the district inclined to vote against Massie because of the way he handles his district office. When he first came into office, he basically said, if I don’t agree with the program , I’m not going to help my constituents access it.

“He got talked down off that, but your chamber of commerce-type people have always wanted to get rid of Massie. You have the Trump thing, but then you have another set that have long wanted to elect somebody else for totally unrelated reasons, so he’s got to watch that flank too.”

Watson still predicts a Massie win, but added: “If he loses, Trump’s going to wave the flag and say that he did it; Trump alone couldn’t have done it. It’s the opponents that Massie’s got, specifically your chamber of commerce Republicans combined with the Trump Republicans.”

The congressman’s defiance has earned him grudging respect from the other side of the political aisle. Linda Vila Passione, 68, a retired teacher originally from New York, said: “I am a dyed-in-the-wool Democrat, but some of the stuff that Massie says when it comes to arguing with the moron in charge is right up my alley.”

Massie and Gallrein’s offices did not respond to requests for comment. When the Guardian visited Massie’s campaign headquarters in a squat brick building at a highway intersection in Florence, Kentucky, a message posted on the door asked that questions be sent by email. Beside it sat a wooden crate containing a stack of Massie yard signs lying upside down.