WASHINGTON — President Trump has given Republicans good reason to tolerate his unruly leadership style. His tax cuts, deregulation push and nomination of conservative judges amount to the most orthodox Republican agenda any president has pursued since Ronald Reagan.
Few had better reason to appreciate Mr. Trump’s results than Charles G. Koch, a billionaire industrialist who is one of the Republican Party’s biggest donors.
Yet Mr. Koch’s simmering frustrations with the president over trade and immigration have now spilled over into an ugly public feud with Mr. Trump and candidates who side with him. By calling Mr. Trump’s trade policies “detrimental” and denouncing divisive leadership, Mr. Koch is making a provocative political move that — be it hardball strategy or more of a ploy — threatens to complicate Republican efforts to hold on to their slim congressional majorities in the November midterm elections.
Mr. Trump hit back on Tuesday by attacking Mr. Koch; his ailing brother and business partner, David; and the powerful political network they founded as “totally overrated” and “a total joke in real Republican circles.”
“I never sought their support because I don’t need their money or bad ideas,” Mr. Trump fumed on Twitter in an early morning series of posts. And several Republicans, including some allies of the Kochs, accused them of self-aggrandizement.
The back-and-forth between the two men began with threats from Mr. Koch and his top political aides over the weekend to withhold support for Republican candidates who do not help enact the free trade, budget-slashing, government-shrinking policies that have always been at the center of the Koch political philosophy but are of little interest to the president. The Koch network has said it plans to spend up to $400 million on politics and policy in the 2018 election cycle.
In a video released to the media during a Koch network retreat in Colorado Springs on Saturday, Mr. Koch was unsparing in his criticism of the kind of nationalist, protectionist trade policies that the president favors. And while he did not mention Mr. Trump’s name, at times he appeared to be speaking directly about the president and many of his supporters.
Mr. Koch denounced a “rise in protectionism” in which countries, organizations and individuals are “doing whatever they can to close themselves off from the new, hold on to the past, and prevent change.”
“This is a natural tendency,” Mr. Koch added, “but it’s a destructive one.”
On Monday the Koch political operation followed up with an opening shot against a high-profile 2018 Republican candidate: Americans for Prosperity, the Koch-funded national grass-roots network, said the group would not be supporting Representative Kevin Cramer of North Dakota in his bid to unseat the Democratic incumbent senator, Heidi Heitkamp, in one of the year’s most competitive races. The group’s president, Tim Phillips, said at the retreat that Mr. Cramer had been “inconsistent” on their issues.
The Koch political network remains generally opposed to many Democratic policies and does not want to see leaders like Nancy Pelosi, the House minority leader, return to power if the Democrats triumph in the midterms. But those who know Mr. Koch’s thinking said that his criticism of Mr. Trump reflects the vast political and personal gulf between the two men. They also echo the widely held beliefs of many conservatives who worry that Mr. Trump is inflicting long-term damage on their cause, and on the country.
Mr. Koch’s unease is a reflection of the wider discomfort and disorientation inside the Republican Party since Mr. Trump stormed the presidential primaries in 2016 and knocked out every candidate the Koch network had supported.
Mr. Trump all but ran against elements of the Koch agenda in 2016, promising support for entitlements, infrastructure and the military. In some ways he has governed like a conventional pro-Koch Republican, especially with some of his cabinet picks like Scott Pruitt, his former chief at the Environmental Protection Agency. But his language on trade and immigration ran counter to the Kochs. And like some other right-leaning organizations and intellectuals, Mr. Koch and his organizations have struggled to find their place in a political party they barely recognize and whose political fortune is now wedded, for better or worse, to Mr. Trump’s.
Despite the hundreds of millions of dollars that the Koch network has spent on politics in recent years, Mr. Koch has always been unnerved at seeing portrayals of himself as a Republican kingmaker, people close to him have said. And over the last few years the Koch brothers, two of the world’s wealthiest men, have tried to cultivate a worldly, civic-oriented image to counter the Democratic Party’s attacks on them as self-interested corporatist puppet masters. Koch Industries, the global energy conglomerate, also began a national marketing campaign to try to soften its image.
But how far Mr. Koch and his groups go in following through with their latest threats was the subject of cynical speculation this week from Republicans and conservatives across a wide spectrum of the party — from pro-Trump leaders and groups to more establishment-aligned interests that usually fight alongside the Kochs in Washington’s legislative trenches.
Scott Reed, the chief political strategist for the U.S. Chamber of Commerce, blasted the Koch threats as a “vanity play of historic proportions.”
“The Koch operation never had a foundation,” Mr. Reed added. “They chased rabbits all over the country with no central set of issues, theme or ideology. Lots of noise and bluster and very little to show for it.”
Stephen K. Bannon, Mr. Trump’s former chief White House strategist and a relentless critic of the older-guard Republican Party leadership, said the Kochs were “the latest to succumb to ‘Trump derangement syndrome,’” a phrase the president and many of his supporters have started using to mock people who are highly critical of Mr. Trump.
“They are trying to weaponize the ‘Never Trump’ movement against Republicans by saying they’ll work with Democrats,” Mr. Bannon added. “And what they’re doing has to be condemned, including by Vice President Pence.”
Vice President Mike Pence, a former congressman and governor of Indiana, has been a longtime beneficiary of Koch donations. His inclusion in the Trump administration, and the ties he retains to the Koch political operation, underscore how difficult it has been to meld the two disparate political orbits.
Marc Short, a former president of the Koch political arm Freedom Partners who joined the Trump campaign in 2016 to work alongside Mr. Pence, recently left his job as the White House legislative affairs director. His tenure was complicated by the way Mr. Trump often treated Republican leaders in Congress as members of the opposition party.
Mr. Phillips, the Americans for Prosperity president, declined to respond to Mr. Trump’s criticism on Tuesday. “We’re focused on advancing policies that break down barriers to success for Americans, not on personal attacks,” he said.
This is not the first time a dispute with Mr. Trump has gotten personal for one of the Kochs. Shortly after the 2016 election, which the Koch network only participated in at the congressional level, snubbing Mr. Trump, David Koch was preparing for a game of golf at the Trump course in West Palm Beach, Fla. But Mr. Trump denied Mr. Koch and his golfing partner, Harry Hurt, a Trump biographer, before they got to the first tee.
If the Koch political operation follows through with its plans to punish more Republicans like Mr. Cramer — network officials pointed out that if this were 2014 or 2016, Mr. Cramer most likely would have received their backing — that could put Republicans in jeopardy elsewhere.
At their weekend retreat, Koch political strategists released a list of the states with Senate races they were committing to: Florida, Missouri Tennessee and Wisconsin. But what that list did not include spoke volumes.
Notably absent was Indiana, where the incumbent Democrat, Senator Joe Donnelly, is facing a Republican businessman, Mike Braun. The race is one Republicans believe offers one of their best opportunities to gain a seat. But Mr. Braun has praised the president’s actions on tariffs.
A Koch endorsement and the accompanying advertising and on-the-ground campaign support that often follows can help swing close races. Koch groups like Americans for Prosperity were built to be vehicles for the conservative grass-roots, even if they rely heavily on paid staff to do their work. And their emphasis on cutting spending, regulations and the size of the government helped elevate fiscal issues to the forefront of the Tea Party-inspired revolts that helped Republicans take control of the House of Representatives in 2010.
That Mr. Koch is being harshly critical of a president beloved by the conservative grass roots, while at the same time endorsing a strategy that could help cost Republicans seats in a close election, struck some activists as strange.
Adam Brandon, president of Freedom Works, another conservative grass-roots group that supports low taxes, smaller government and free trade, said that a Democratic-controlled House would not be helpful on any of those issues, whereas a Republican majority would be.
“If you lose that majority, I don’t know how that helps,” Mr. Brandon said. “This is a unity moment heading into these midterms.”
Mr. Brandon explained the contradictory emotions many Republicans today are facing, balancing the good of the Trump administration with the bad. “Here he is, the same president who’s done more to deregulate than any president in history, cut taxes — and now he’s pushing tariffs. It’s left a lot of people scratching their heads.”
Mr. Brandon reasoned that he can look past it. “We’re getting a whole lot more that we like than that we don’t like,” he said.
An earlier version of this article misstated the states with Senate races to which the Kochs were committing their political efforts. Nevada is not one of those states.