WASHINGTON (Reuters) - U.S. President Donald Trump on Tuesday slammed the powerful Koch-led political operation as “globalist” and “a total joke,” rejecting the conservative group amid signs of a growing public fissure between the president and business over trade.

Trump’s comments follow news media reports that some officials within the Koch donor network - which has spent millions to help elect Republicans - are concerned the president’s trade policies could fuel a recession and want to scale back support of Republican candidates.

The Kochs are not the only business group critical of the president’s trade policies. The U.S. Chamber of Commerce, the nation’s largest business lobby, has publicly criticized the billions of dollars worth of tariffs the administration has targeted at China, Canada, Mexico and the European Union.

Trump has also escalated criticism in recent weeks of American companies that appear critical of his trade policies, including firing off threats at motorcycle manufacturers Harley Davidson HOG.N.

The public spat with the Kochs comes less than four months before the Nov. 6 midterm congressional elections that have Trump’s fellow Republicans seeking to maintain control of both chambers of Congress and lay bare the ongoing internal debate in the Republican Party about trade policy.

The Koch brand - including Koch Industries, the second-largest privately held American company - has become synonymous in political parlance with pro-business policies and libertarian ideology. The company and the Koch political operations have pushed relentlessly for lower taxes, less regulation and free trade.

The Koch-backed network of political organizations - which were founded by brothers Charles and David Koch but now include a larger group of donors - have historically spent millions of dollars backing like-minded Republican candidates for office.

Charles Koch (L) and David Koch are seen in this combination picture. REUTERS/Freedom Partners Chamber of Commerce/Handout/Carlo Allegri

But as Trump has sought to pull his party toward more protectionist trade positions, backers of free trade policies like the Koch network have been reluctant to provide support. That could mean Republican candidates who seek to closely align themselves with Trump on trade are forgoing backing from groups like the Koch network.

“The globalist Koch Brothers, who have become a total joke in real Republican circles, are against strong borders and powerful trade. I never sought their support because I don’t need their money or bad ideas,” Trump wrote on Tuesday in a post on Twitter.

“Their network is highly overrated, I have beaten them at every turn.”

The Koch network largely ignored the criticism.

“We support policies that help all people improve their lives,” James Davis, a spokesman for the Koch network, said in a statement. “We look forward to working with anyone to do so.”

At the center of the latest flare between the Kochs and Trump is support for Kevin Cramer, a Republican running for the U.S. Senate in North Dakota against incumbent Democrat Heidi Heitkamp.

The Koch-backed group Americans for Prosperity ran television ads this summer in North Dakota thanking Heitkamp for supporting deregulation - a move that stopped short of an endorsement of the Democrat but that provoked criticism from Republicans.

The same group has announced this weekend they will not support Cramer.

“It was very disappointing to see yesterday that they are not going to support Kevin Cramer in this all too important North Dakota (U.S.) Senate race,” said Ronna McDaniel, the chair of the Republican Party.

The billionaire industrialist brothers distanced themselves from Trump during the 2016 presidential election, in part over his divisive rhetoric toward Muslims and others.

Charles Koch has taken the lead after his younger brother, David, stepped down from their political group and their company earlier in June due to poor health.

But once Trump took office, he appeared to have made peace with the Koch network. The Koch network campaigned heavily for passage of tax cuts that Trump signed into law last year and praised his judicial picks.

The peace deal, however, appeared to be dissolving after the Koch network launched a multimillion-dollar campaign to oppose Trump’s tariffs.