Neither representatives of Koch Industries or officials from the political network responded to a request for comment.
Their company, Koch Industries, is the second largest privately owned business in the U.S. and has interests ranging from pipelines to paper towels.
While the move echoed across the political world, Republican operatives quietly dismissed the practical impact of the Koch's decision on the North Dakota Senate race, where Cramer's campaign believes he has a double-digit lead in the deep-red state against the Democratic incumbent. Heidi Heitkamp. Heitkamp is one of the most vulnerable Democratic seats in the midterm elections and if Cramer takes her seat, it could help them keep the majority. The company and the Koch political operations have pushed relentlessly for lower taxes, less regulation and free trade.
That's not to say they're punishing every Trump loyalist in the 2018 election season. "But if you're a Democrat and you stand up to Elizabeth Warren and corral enough votes for financial reform. you're darn right we'll work with you".
Colorado-based energy investor Chris Wright, a longtime Koch donor, said the Republican Party may have lost its way in the age of Trump.
Trump's policies on trade in particular have provoked ire among some Republicans, especially those in states most affected by retaliatory tariffs enacted by China, Canada, the European Union and beyond.More news: Egyptian zoo denies their 'zebra' is a donkey after photo goes viral
Some Trump loyalists were furious at perceived contradictions in the Koch network's behaviour and anxious that it could complicate the president's 2020 re-election.
Fifteen years later, the network has grown to encompass more than 700 donors who each contribute at least $100,000 annually to Koch-linked groups.
Trump alleged that his policies have "made them richer" but that they "want to protect their companies outside the US from being taxed" while he supports the American worker.
He called out the White House and Trump-allied GOP lawmakers, particularly over trade policy and increased federal spending, and added that "the divisiveness of this White House is causing long-term damage".
"If this were 2016, we likely would have gone ahead and endorsed" Cramer, said AFP President Tim Phillips.
Charles Koch told reporters in recent days that he cared little for party affiliation and regretted supporting some Republicans in the past who only paid lip service to conservative principles.