By JOE WILLIAMS, REMA RAHMAN and LINDSEY McPHERSON

Senate Republicans are hinging their support on a “skinny” bill to repeal the 2010 health care law on assurances that the chamber would go to conference with the House on a broader bill with replacement measures.

But just hours before the measure is expected to be voted on, it is not clear that such a strategy is definitive.

It is a massive gamble for GOP senators who have opposed prior health care proposals from Senate leadership and view the conference with the House as a chance to continue the dialogue. Should the still-unreleased legislation actually be signed into law, experts have warned that the rumored outline of the bill could collapse the individual health insurance market.

Four Republican lawmakers — Sens. Lindsey Graham of South Carolina, Ron Johnson of Wisconsin, John McCain of Arizona and Bill Cassidy of Louisiana — vowed to vote against the “skinny” bill if they do not get an adequate commitment from the House to go to conference on the legislation. 

Senate Majority Leader Mitch McConnell can only afford to lose the support of two GOP members. 

“We’ve been asked by our leadership for days now to vote on the least common denominator – the skinny bill – because, the pitch is if you vote for the skinny bill then we can go to conference,” Graham said. “There’s increasing concern on my part and others that what the House will do is take whatever we pass…not take it to conference, go directly to the House floor, vote on it, and that goes to the president’s desk.”  

He called the policy of the slimmed down legislation a “disaster.” 

“The skinny bill as a replacement for Obamacare is a fraud,” Graham said. 

Lawmakers leaving a Republican Senate lunch said they were given assurances that a conference with the House would happen, but could not say for certain.

“We had a good discussion. The intent of the leadership is to get it into conference, which is, was, my concern,” Sen. Rob Portman of Ohio said. “I suppose, technically, it’s a decision only the House can make, but that’s their intent and they said they had good discussions with House leadership on it.”

In a statement, Portman said he would support a skinny bill to “move this process to a House-Senate conference.” 

A McConnell spokesman directed questions on whether a conference would occur to House Speaker Paul D. Ryan.

A Ryan spokeswoman said the strategy is “something we’re taking steps to prepare for should we choose that route after first discussing with the members of our conference.”

Ryan, at his weekly Thursday press conference, punted on the question.

“We’re going to reserve judgement until we see what the Senate actually produces,” the Wisconsin Republican said.

Meanwhile, House members were advised that the chamber’s schedule could change pending action on the health care bill, as Republican lawmakers said they were waiting to see what is produced in the Senate before weighing in.  

Rep. Mark Walker of North Carolina, for example, said he anticipated the health care bill to go to conference when it comes to the House as opposed to it going to the floor for a vote before the August recess.

But Walker, who chairs the Republican Study Committee, said he wanted to see whether the bill had “enough skin on the bone of this skinny deal” before determining where he would stand.

The “skinny repeal” deal is ugly to the bone.

— Rep. Mark Walker (@RepMarkWalker) July 27, 2017

Having a hard time recalling GOP Senators promising a “skinny repeal” of ACA. If they pass, we should go to conference and keep our promise.

— Rep. Mark Walker (@RepMarkWalker) July 27, 2017

‘Skinny’ mystery

Democratic and Republican members took to the Senate floor Thursday to give speeches rehashing many of the partisan talking points that have already been voiced over the past few months.

While that was ongoing, McConnell continued to work in secret to try to find consensus among the GOP conference on a bill that would, aides say, repeal the individual and employer mandates in the 2010 health care law, defund Planned Parenthood and repeal the law’s prevention fund.  

The so-called vote-a-rama, during which virtually unlimited amendments could be offered by either party, is set to begin Thursday evening once the 20 hours of debate provided under the fast-track reconciliation process expires.

Democrats have vowed not to offer any amendments until Republican leaders file their skinny bill as an amendment, leaving the chamber largely in a stalemate.

GOP members appeared uncertain on the actual strategy and were left scrambling for certainty over whether they would have a chance to craft a new package should they vote for the slimmed-down bill. But that did not stop many from voicing support for the skinny-bill approach.

“I think everyone understands this is a lifeline to conference. I think we want assurances of that and when they have assurances of that, and I think they will get them … then I think people will support whatever it is that will keep our efforts alive,” Tennessee Sen. Bob Corker told reporters.

South Carolina Sen. Lindsey Graham on Thursday was trying to determine whether legislation he worked on with fellow Republican Sen. Bill Cassidy of Louisiana would be permissible under budget rules.

“Mitch McConnell told our conference that he had spoken to Paul Ryan and Paul Ryan intends to go to conference. So it’s very important that I know before our vote, is my amendment conference-able and there will be a conference because the worst possible outcome is to pass something that most of us believe is the placeholder and it becomes the final product,” Graham told reporters.

Graham said trying to fix the skinny bill later is a “nonstarter” because it “would destroy insurance markets and not even remotely replace Obamacare.”

“This is going to be a trust-but-verify situation with me,” the South Carolina Republican said.

Other members — after weeks of frustration over the current process — appear to be completely resigned whatever leadership puts forward.

“I would be uncomfortable voting for a bill that I think further hastens the collapse of the marketplace,” Sen. Ron Johnson of Wisconsin said. “I’m not going to defend this place, I’m not going to this process, I’m not going to even defend the product that we are talking about right now.”

Andrew Siddons and Lauren Clason contributed to this report.