WASHINGTON – An effort by Speaker Paul Ryan to mend a dispute between House and Senate Republicans over the party’s drive to repeal the Obama health care law is receiving mixed reviews from a group of Republican senators, leaving party leaders’ hopes for pushing an initial measure through the Senate up in the air.

Senate Majority Leader Mitch McConnell, R-Ky., was hoping to push a modest bill through the Senate peeling back pieces of President Barack Obama’s health care law. Several Republican senators said they were willing to vote for it only with a promise that the House would not approve it and send it to President Donald Trump for his signature. Instead, they are demanding House-Senate talks aimed at producing a wider-ranging measure.

Ryan, R-Wis., sent senators a statement saying that if “moving forward” requires talks with the Senate, the House would be “willing” to do so. But shortly afterward, his words received varied responses from three Republican senators who’d insisted on a clear commitment from Ryan.

“Not sufficient,” said Sen. John McCain, R-Ariz., who returned to the Capitol Tuesday to provide a pivotal vote that allowed the Senate to begin debating the health care bill, a paramount priority for Trump and the Republican. The 80-year-old McCain had been home in Arizona trying to decide on treatment options for brain cancer.

Sen. Lindsey Graham, R-S.C., initially said “not yet” when asked if he was ready to vote for the scaled-back Senate bill. But later, he told reporters that Ryan had assured him and others in a phone conversation that the House would hold talks with the Senate.

“I feel comfortable personally. I know Paul; he’s a man of his word,” said Graham.

“Let’s see how everything turns out here, guys,” Sen. Ron Johnson, R-Wis., told reporters.

The convoluted developments played out as a divided Senate debated legislation to repeal and replace Obama’s Affordable Care Act. With Democrats unanimously opposed, the slender 52-48 Republican majority was divided among itself over what it could agree to.

After a comprehensive bill failed on the Senate floor, and a straight-up repeal failed too, McConnell and his top lieutenants turned toward a lowest-common-denominator solution known as “skinny repeal.” It would package repeal of a few of the most unpopular pieces of the 2010 law, along with a few other measures, with the goal of getting something, anything, out of the Senate.

That would be the ticket to negotiations with the House, which passed its own legislation in May.

But that plan caused consternation among Republican senators after rumors began to surface that the House might just pass the “skinny bill,” call it a day and move on to other issues like tax reform after frittering away the first six months of Trump’s presidency on unsuccessful efforts over health care.

Ryan responded not long after with a discursive and far from definitive statement that blamed the Senate for being unable to pass anything, but said, “if moving forward requires a conference committee, that is something the House is willing to do.”

“The reality, however, is that repealing and replacing Obamacare still ultimately requires the Senate to produce 51 votes for an actual plan,” he said.

There was no immediate response from Graham, McCain or Johnson.

Sen. Mike Rounds, R-S.D., said he pretty much took Ryan’s statement as a commitment, but wanted to talk to other senators first.

“If the Speaker says they’re not going to the floor with it, then they’re not going to the floor,” Rounds said. “The Speaker controls the floor.”

The Senate measure has not been finalized, but senators have said it could eliminate Obamacare’s mandate for individuals to carry insurance and temporarily halt the requirement that larger employers to offer it.

Lobbyists said Republicans were also planning to include a one-year ban on federal payments to Planned Parenthood, extra money for community health centers and waivers for states to permit insurers to sell policies with far narrower coverage than current law allows.

But leaders were encountering problems. The Senate parliamentarian advised that the waiver language violates chamber rules, meaning Democrats could block it. And plans to eliminate Obama’s medical device tax could be abandoned because Republicans need that money for their package.

The insurance company lobby group, America’s Health Insurance Plans, wrote to Senate leaders Thursday saying that ending Obama’s requirement that people buy insurance without strengthening insurance markets would produce “higher premiums, fewer choices for consumers and fewer people covered next year.”

And a bipartisan group of governors including John Kasich of Ohio and Brian Sandoval of Nevada also announced against it.

On their own, the changes in the skinny bill could roil insurance markets. Yet the scenario at hand, with senators trying to pass something while hoping it does not clear the House or become law, was highly unusual.

“We’re in the twilight zone of legislating,” said Democratic Sen. Claire McCaskill of Missouri.

The back-and-forth played out as the Senate prepared for a bizarre Capitol Hill ritual, a “vote-a-rama” on amendments that promised to last into the wee hours of Friday morning — at the end of which, the path ahead would perhaps be clearer.