President Trump ripped conservative mega-donors Charles and David Koch one day after the political network formed by the billionaire brothers said it would not support a Republican Senate candidate in North Dakota.

"The globalist Koch Brothers, who have become a total joke in real Republican circles, are against Strong Borders and Powerful Trade," Trump said in a series of tweets early 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. Their network is highly overrated, I have beaten them at every turn," he added.

"They want to protect their companies outside the U.S. from being taxed, I'm for America First & the American Worker - a puppet for no one. Two nice guys with bad ideas. Make America Great Again!"

Americans for Prosperity President Tim Phillips announced at a donor summit on Monday in Colorado Springs, Colo., that the network would not support Rep. Kevin Cramer (R-N.D.) in his bid to unseat incumbent Sen. Heidi Heitkamp (D-N.D.).

Phillips cited Cramer's support for the Export-Import Bank, the farm bill and the $1.3 trillion spending package for the decision.

"He's inconsistent across the board on these issues," Phillips said. "We can't support him at this time and we've met with his team, explained this and lobbied them on this."

Heitkamp is seen as one of the most vulnerable Senate Democrats up for reelection. Trump carried North Dakota by more than 30 points in 2016.

The Koch network is backing GOP Senate candidates in Wisconsin, Missouri, Tennessee and Florida.

Charles Koch said on Sunday that his network would be more aggressive in going after Republicans who have not adhered to fiscally conservative principles.

"I regret some of the [lawmakers] we have supported," Koch told a small group of reporters in a rare interview. "We're going to more directly deal with that and hold people accountable."

Koch also said he's hopeful his network can support more Democrats going forward.

Updated at 7:05 a.m.