Republican senators are pushing for major changes to a bipartisan deal to fund Obamacare payments in an effort to win President Trump's support.

But some Democrats were skeptical of making any alterations to the deal, which was formally introduced in Congress on Thursday.

Sen. Lamar Alexander, R-Tenn., and Patty Murray, D-Wash., introduced the legislation that funds cost-sharing reduction payments to Obamacare insurers for two years in exchange for changes to the law. The legislation has 24 sponsors evenly divided among Republicans and Democrats.

Senate Minority Leader Chuck Schumer said Thursday the legislation has the support of at least 60 senators, enough to break a filibuster because all 48 Democrats are expected to support it.

But the legislation is likely to see some changes, especially since Trump opposes the deal as it stands now. Trump derided the payments, which reimburse insurers for lowering co-pays and deductibles for low-income Obamacare customers, as bailouts of insurance companies.

Sens. Bill Cassidy, R-La., and Lindsey Graham, R-S.C., issued a statement that said they are working with Sen. Ron Johnson, R-Wis., on changes to the legislation to satisfy Trump and House Speaker Paul Ryan, who is also opposed.

"We recognize this short-term stabilization will not pass unless concerns of the House are addressed," said Graham and Cassidy, who are co-sponsoring the Alexander-Murray legislation.

Trump made several demands for what needs to be included in the legislation to win his support. Those include relief from the individual and employer mandates and "meaningful flexibility" for states to waive Obamacare regulations.

The bill includes several provisions that aim to ease the process for states to waive Obamacare regulations, and it is not clear what changes the president wants.

Johnson already was working on several proposals that address some of Trump's concerns, including delaying enforcement of the individual and employer mandate.

It also calls for expanding the duration of short-term plans from 90 days to 364 days and expanding the use of health savings accounts.

Johnson previously told the Washington Examiner that he was drafting the principles with an eye on the House, which has been critical of the deal because of the cost-sharing payments.

But a major question mark is whether Democrats would be open to making any of the changes. Several Democratic senators were skeptical.

Sen. Tom Carper, D-Del., a co-sponsor, said that he wasn't familiar with the president's demands and would prefer to keep the deal where it is.

"The people who stand to benefit most from the compromise … are folks who live in red states," he told the Washington Examiner.

Sen. Chris Murphy, D-Conn., who is not a co-sponsor, was flummoxed by the timing of Trump's demands, which he said he has not seen.

"Why didn't he make those demands two weeks ago?" Murphy asked. "We should move forward with this bill and put it on his desk."

Murphy added that time is running out for the bill to have an impact on 2018 open enrollment, which starts Nov. 1 and ends Dec. 15.

"If we go out and renegotiate this package we won't be able to affect rates this year and won't restore the marketing in time for open enrollment," he said. "We gotta move and we've gotta move fast."

The bill restores more than $100 million in Obamacare ad and outreach funding.

Alexander told reporters Thursday that he hasn't made a decision on whether to pursue a markup on the bill in a committee. He added if the bill does go through a committee, it likely would be the Senate Finance Committee helmed by Sen. Orrin Hatch, R-Utah, who opposes it.

Sen. John Thune, R-S.D., the third-ranking GOP senator, predicts there will be a markup.

"I think our folks will want to have regular order on that," he said.