Charles and David Koch's wealthy network of donors will spend approximately $400 million to push it conservative agenda forward in the upcoming 2018 midterm elections, the group told Fox News on Saturday.

"Three-hundred million to $400 million for this cycle for politics and policy - we believe we're headed to the high end of that range," said Tim Phillips, who oversees Americans for Prosperity, a group funded by the conservative billionaire brothers.

"What we're urging Republicans in the House and the Senate to do is to be bold, to go big," Phillips said, stressing healthcare and tax reform.

"It gives them the opportunity to point to real accomplishments when they get to 2018," he said.

This announcement on political and policy spending comes shortly after Republicans in the upper chamber rolled out their version of an ObamaCare repeal-and-replace bill on Thursday.

Many conservatives want to scale back or cut Medicaid, a health insurance program that largely covers low-income people, as well as some elderly and disabled people.

Charles Koch and other members of his team are having meetings with their donors in Colorado Springs.

They told the news outlet that the White House has welcomed their input on the Senate healthcare bill, unlike during the House healthcare debate that took place earlier this spring before it passed.

At the time when they felt their input was being taken into consideration, the Kochs reportedly stood behind House Republicans running in 2018 who opposed the House healthcare measure.

"We did want to remind them that this was a promise that had been made to repeal ObamaCare during four consecutive national elections," Phillips continued. "It was important to be a little more demonstrative."

While the Koch team would prefer more ObamaCare provisions to be repealed and replaced, they say they are now working with the Trump administration on the bill.

The Senate, in which Republicans hold the majority, could vote on the new healthcare bill as early as next week.

- Updated: 5:05 p.m. to include mention of funds going towards policy efforts.