Senate Republicans are weighing a two-step process to replace the Affordable Care Act that would postpone a repeal until 2020, as they seek to draft a more modest version than a House plan that nonpartisan analysts said would undermine some insurance markets.

Republicans, in the early stages of private talks on the Senate plan, say they may first take action to stabilize premium costs in the ACA’s insurance exchanges in 2018 and 2019. Major insurers have said they will leave the individual market in vast regions of states including North Dakota, Iowa and Missouri.

A Senate plan is likely to continue subsidies that help low-income Americans with copays and deductibles, said Sen. John Thune, R-S.D.

White House budget director Mick Mulvaney said Thursday the administration hasn’t committed to paying subsidies due in June — which would create additional uncertainty for insurers as they set rates for next year.

“There clearly has to be a short-term solution that works with the transition until some of our long-term policy changes can take effect,” Thune said. “There’s got to be certainty in the marketplace.”

The private Senate GOP negotiations include a 13-member leadership-controlled working group as well as almost daily closed-door discussions among all Senate Republicans. In addition, Republican Sen. Susan Collins of Maine has convened bipartisan talks with about a dozen senators.

Republicans in the Senate are stepping up their efforts to build consensus after the nonpartisan Congressional Budget Office said Wednesday that the House plan narrowly passed May 4 would result in 23 million more people without insurance and, in some states, plans that are too costly for older or sicker people.

Democrats in both chambers are united against efforts to replace the ACA and said the CBO assessment provides added ammunition for the Senate fight. Senate Minority Leader Chuck Schumer said the report should be the “final nail in the coffin” in the Republican drive to repeal the ACA.

“The report makes clear: Trumpcare would be a cancer on the American health care system, causing costs to skyrocket, making coverage unaffordable for those with pre-existing conditions and many seniors, and kicking millions off their health insurance,” he said.

Senate Republican leaders say they expect to try to pass a bill with only GOP votes. The party controls the Senate 52-48, and the parliamentarian will determine which parts of a bill could advance under streamlined procedures that can pass with 50 votes plus Vice President Mike Pence’s tiebreaker.

Whether the GOP can attract 50 votes remains to be seen. Senators have indicated the talks have spent little time on perhaps the toughest issue: How to pay for a plan that would cover more people and offer lower premiums than the House bill. That would require retaining some of about $800 billion in ACA taxes that the House measure repeals, or finding other cost savings in the federal budget.

“I think we ought to try to look for savings anywhere we can find them,” said Senate Finance Committee Chairman Orrin Hatch, R-Utah. “But my experience is that we don’t find many savings.”