(Bloomberg) -- Senate Republicans are gearing up to try to passa stripped-down Obamacare repeal plan many hope won’t becomelaw.

Instead -- after going through an all-night session of chaoticamendment votes -- the plan is to get a bill through the Senate and then negotiate withthe House on a broader agreement to repeal and replace the Affordable Care Act, a number of Republicansenators said Thursday.

"The worst possible outcome is to pass something that most of usbelieve is a placeholder and it becomes the final product," saidRepublican Senator Lindsey Graham of South Carolina.

Graham said he would support the measure as long as he getspersonal assurances from House Speaker Paul Ryan of Wisconsin thatany bill the Senate passes will go to a House-Senate conferencecommittee.

Struggling under their slim 52-48 majority, Republicans say thisweek’s debate -- including Thursday night’s blizzard of amendmentvotes known as vote-a-rama -- may ultimately lead to a"skinny" bill that merely ends the mandate that all Americanshave insurance or pay a penalty, along with a few otherprovisions.

‘Long night’

"This is likely to be a very long night," Majority Leader MitchMcConnell on the Senate floor as the chamber started the day’ssession. "It will not signal the end of our work, not yet."

Senator John Cornyn of Texas, the No. 2 Republican leader, saidRepublicans were discussing how many elements of an Obamacarerepeal they must include to get enough support to pass.

The House could choose to pass the bare-bones repeal and send itto President Donald Trump, but a number of senators sought toensure that wouldn’t happen. Ohio’s Rob Portman and other SenateRepublicans said they would vote for a "skinny" Obamacarereplacement only as a steppingstone to talks with the House, whichpassed a broader Obamacare overhaul, H.R. 1628, in May.

"I’m for a real replacement" of Obamacare, Portman said.

Senator Roy Blunt of Missouri, a member of the Republicanleadership team, said a skinny plan might also eliminateObamacare’s requirement that most employers offer insurance totheir workers, as well as some language allowing states morewaivers to modify aspects of Obamacare. He said it is unlikely toinclude a repeal of a medical device tax that had been underconsideration.

Democrats expressed amazement that Senate Republicans wouldvote for an important piece of health legislation only on conditionthe House would virtually ignore it.

"This is ridiculous," said Senator Claire McCaskill, a MissouriDemocrat. "It’s like we’re in the twilight zone oflegislating."

The behind-the-scenes talks contrasted with what was takingplace on the Senate floor, where lawmakers were debating whether toreplace Obamacare with a broad revision or even repeal itoutright.

Early votes underscored the majority party’s difficulty inpushing through a GOP-only bill amid unified Democraticopposition.

The Senate rejected a fuller repeal of Obamacare 45-55Wednesday. Seven Republicans voted against it, including SenateHealth Chairman Lamar Alexander of Tennessee and Senator JohnMcCain, who returned to Washington from his home state of Arizonaafter a brain-cancer diagnosis to help advance the debate.

Late Tuesday, a 43-57 Senate vote swept aside a revised versionof McConnell’s Obamacare replacement, a measure negotiated insecret during weeks of tense GOP talks. Hours earlier, senatorsbarely agreed to start the debate on a 51-50 vote with VicePresident Mike Pence casting a tie-breaker after two Republicansdefected.

The Senate on Thursday defeated, 0-57, a "Medicare for all"amendment proposed by Republicans even though enacting such asingle-payer system is a longtime goal of many Democrats.Independent Senator Bernie Sanders of Vermont -- a single-payerbacker -- called the amendment a "sham" that Republicans had nointention of passing.

Bigger challenges await on the Senate floor, including thevote-a-rama, a fusillade of votes on dozens if not hundreds ofamendments. Democrats may offer poison pills, and other proposalsmight divide Republican moderates and conservatives.

CBO estimate

Senate Minority Leader Chuck Schumer of New York warned that thepassage of a "skinny repeal" alternative is a gambit to get Senateand House Republicans together in talks on a broader replacementplan.

Schumer’s office put out a Congressional Budget Office estimateof a bill that mirrors Republicans’ description of such a measure-- one that would eliminate the individual and employer mandates,repeal the medical device tax and defund Planned Parenthood. TheCBO said such a measure would result in 16 million Americans losingtheir insurance, compared to the 22 million envisioned under themost recent version of McConnell’s replacement bill.

It’s not certain the splintered Republican caucus would agree tosupport a pared-back Obamacare repeal. Senator Shelley MooreCapito of West Virginia said she was unsure if she can support sucha bill.

A plan to repeal only a few parts of Obamacare isn’t uniformlyembraced by the House -- particularly since some senators said theyhoped the House would accept it as the most Republicans can do tofulfill their campaign promise to ax Obamacare.

House Freedom Caucus Chairman Mark Meadows of North Carolinasaid Thursday the House would "absolutely not" send a "skinnyrepeal" of Obamacare straight to Trump’s desk.

"Going to conference may have some merits; we are discussingthat now," Meadows said.

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