WASHINGTON — Senate Republicans and the White House pressed ahead Tuesday with their suddenly resurgent effort to undo the Affordable Care Act, even as their attempt was dealt a setback when a bipartisan group of governors and several influential interest groups came out against the proposal.

Powerful health-care groups continued to rail against the bill, including AARP and the American Hospital Association, both of which urged a no vote. But it was unclear whether the opposition would ultimately derail the attempt, as key Republican senators including Lisa Murkowski of Alaska said they had yet to make up their minds.

The measure marks the last gasp of Republican attempts to dramatically gut Obama’s Affordable Care Act, which has added millions of people to the ranks of the insured through a combination of federally subsidized marketplaces and state-level expansions of Medicaid, leading to record lows in the number of those without health insurance. The Graham-Cassidy bill – named for Sens. Lindsey Graham, S.C., and Bill Cassidy, La. – would convert funding for the ACA into block grants for the states and would cut Medicaid dramatically over time.

TWO MONTHS AFTER FAILED REPEAL

The bill – coming two months after a previous failed repeal effort in the Senate – is the subject of a last-ditch lobbying push by Senate Majority Leader Mitch McConnell, R-Ky., and the Trump administration, led by Vice President Mike Pence, before a Sept. 30 deadline for Senate action.

In a letter to Senate leaders, the group of 10 governors argued against the Graham-Cassidy bill and wrote that they prefer the bipartisan push to stabilize the insurance marketplaces that Sens. Lamar Alexander, R-Tenn., and Patty Murray, D-Wash., had been negotiating before talks stalled Tuesday evening.

The governors who signed the bill are particularly notable, since some are from states represented by Republican senators who are weighing whether to back the bill. Among the signers were Alaska Gov. Bill Walker, I, who holds some sway over Murkowski, a potentially decisive vote who opposed a previous Republican effort to repeal and replace the Affordable Care Act.

Nevertheless, Murkowski said Tuesday afternoon that she was still weighing her options and explained how her position on the bill might ultimately differ from her opposition to the repeal effort that failed dramatically in July.

“If it can be shown that Alaska is not going to be disadvantaged, you gain additional flexibility. Then I can go back to Alaskans, and I can say, ‘OK, let’s walk through this together.’ That’s where it could be different,” she said.

But Murkowski, who has been in close contact with Walker, said she did not yet have the data to make such a determination. Alaska’s other Republican senator, Dan Sullivan, said he was still mulling whether to support the bill.

On the other side, a group of 15 Republican governors announced their support for the Senate bill Tuesday evening. The list includes Kentucky Gov. Matt Bevin, R, whose backing could help influence Sen. Rand Paul, R-Ky., who has frequently criticized the legislation for failing to fully repeal the ACA.

On Tuesday, Pence traveled from New York, where he was attending the annual United Nations General Assembly, to Washington with Graham in a sign of the White House’s support for the proposal.

“My message today is I want to make sure that members of the Senate know the president and our entire administration supports Graham-Cassidy,” Pence told reporters on the flight. “We think the American people need this.”

Graham added that President Trump called him at 10:30 p.m. Monday.

“He says, ‘If we can pull this off, it’ll be a real accomplishment for the country,’ ” he said.

Trump has played a limited role in building support among senators in recent days, but it is possible that his participation will increase as a potential vote nears. He has, however, been in touch with some governors, including a weekend call with Arizona Gov. Doug Ducey, R, according to aides.

‘OPPORTUNITY EXPIRES’ SEPT. 30

Pence attended the weekly Senate Republican policy luncheon, where he said the current health-care system is collapsing and the bill fulfills key Republican promises to return control to states and rein in federal entitlement programs, according to several Republican senators.

Afterward, McConnell declined to ensure a vote on the bill but said his team is working to secure sufficient support.

“We’re in the process of discussing all of this. Everybody knows that the opportunity expires at the end of the month,” said McConnell, referring to the limited window Republicans have to take advantage of a procedural tactic to pass a broad health-care bill without any Democratic support.

Democrats say the ACA needs modest improvements by Congress but is working well overall, and they have railed against a process in which Republicans are pressing ahead with few hearings on legislation that would affect an industry that accounts for about a sixth of the U.S. economy.

The current bill would give states control over billions in federal health-care spending and enact deep cuts to Medicaid. The Medicaid cuts in particular are a major source of concern to the governors, both in terms of imposing a per capita limit on what states would receive and putting restrictions on how they could spend any federal aid on their expanded Medicaid populations.

Medicaid was expanded under the ACA to provide states with generous funding if they opted to cover adults earning up to 138 percent of the poverty level. Many Republican-led states decided against an expansion following a Supreme Court decision allowing them to opt out.

The fact that the bill also would bar states from taxing health-care providers to fund their Medicaid programs posed a problem for several governors.

Louisiana’s health secretary sent a letter to Cassidy on Monday saying their state could see disproportionate cuts with significant impacts on people with pre-existing or complex and costly conditions.

“This would be a detrimental step backwards for Louisiana,” wrote Rebekah Gee, who posted her letter on Twitter on Monday.