The Republican National Committee sent a withering memo to party contributors Thursday, warning donors against investing resources in the Koch political network after their conservative advocacy group lambasted President Donald Trump and declined to support a GOP candidate running in a key Senate race.

This broadside from the party aimed at one of its most generous donor groups – plus a stream of tweets attacking the Kochs from Trump himself – stemmed from the Koch’s three-day donor network meeting held last weekend at The Broadmoor hotel in Colorado Springs.

“Some groups who claim to support conservatives forgo their commitment when they decide their business interests are more important than those of the country or Party,” RNC Chairwoman Ronna Romney McDaniel wrote in the note, which was obtained by Politico.”This is unacceptable.”

> RELATED: More from Kochs’ Colo. meeting: They won’t back GOP Senate hopeful; Trump lashes out

She also knocked the Koch network’s data program, cautioning that entities attached to billionaire libertarian-leaning philanthropist Charles Koch could “weaponize that data against Republicans if their business interests conflicted with electing Republicans.”

The demonstration of flared tensions comes as Americans for Prosperity indicated over the weekend at the Koch conference that it would be open to supporting candidates other than Republicans in the future, pledging to spend about $400 million on the 2018 midterm election cycle.

It also announced it would not back U.S. Rep. Kevin Cramer, R-N.D., in his bid to unseat vulnerable incumbent Democratic Sen. Heidi Heitkamp – a race seen as key to helping the GOP avoid a Democratic takeover of the Senate.

“I don’t care what initials are in front or after somebody’s name,” Koch said on the weekend.

> RELATED: More on Koch Colo. conference: Another blast from Trump on trade criticism

James Davis, a Koch spokesman, told Politico on Thursday that the group’s calculus in choosing which political candidates to boost has not changed.

“We have a long-term commitment to unite around issues that will help people improve their lives,” he said. “Just as we have in the past, we will work together with the president, elected officials and others where we agree. And, where we disagree, we will do so in a civil way.”

In a video presented at the Broadmoor event, Charles Koch took Trump to task over his trade and tariff policies, saying they could hurt the U.S., economy.

Since then, Koch has been on the receiving end of several angry presidential tweets mocking his supposedly dwindling influence in GOP politics.

> RELATED: Billionaire conservative funder Koch takes on Trump over trade at Colorado meeting

“The globalist Koch Brothers, who have become a total joke in real Republican circles, are against Strong Borders and Powerful Trade,” Trump tweeted Tuesday. “I never sought their support because I don’t need their money or bad ideas. They love my Tax & Regulation Cuts, Judicial picks & more.”

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

The Kochs and their network did not endorse Trump in 2016.

Colorado Politics contributed.