Washington (CNN)President Donald Trump says the Republican plan to repeal and replace the Affordable Care Act "guarantees" coverage for Americans with pre-existing conditions -- a claim that could undercut the legislation the White House is currently pushing on Capitol Hill.

"Pre-existing conditions are in the bill. And I mandate it. I said, 'Has to be,'" Trump told CBS's John Dickerson on "Face the Nation" Sunday.

Pressed further, Trump said that "we actually have a clause that guarantees" coverage for those with pre-existing conditions. Trump also said the health care legislation is "changing."

Trump's comments come days after moderate New Jersey Rep. Tom MacArthur and leaders of the conservative House Freedom Caucus cut a deal that would require insurers to cover those with pre-existing conditions; but, unlike the mandate under Obamacare, insurers could charge them higher rates than others in the plan if they allow their coverage to lapse.