The Senate embarked on a freewheeling process to rewrite the Affordable Care Act on Tuesday, as Republicans overcame deep divisions to bring their proposals up for debate by the narrowest possible margin.

But those same schisms threatened to leave the party far short in the coming days of its ambitious goal to undo major parts of the ACA, which the GOP has been vowing for seven years to dismantle. On Tuesday night, just hours after opening debate, Senate Republican leaders were unable to pass a bill that they had spent weeks crafting but that never gained sufficient traction with the rank and file.

Fifty-seven senators — including nine Republicans — opposed the updated version of the measure known as the Better Care Reconciliation Act (BCRA), while 43 supported it, portending a difficult road ahead for the GOP rollback effort.

The earlier vote to start debate marked a momentary political victory for Senate Majority Leader Mitch McConnell (R-Ky.) and President Trump. The president managed to resuscitate the GOP’s months-long effort to unwind President Barack Obama’s signature 2010 law by convincing more than half a dozen wavering senators that they could not afford to walk away from an enduring political promise. Republicans passed the procedural hurdle by a slim 51-to-50-vote margin, with Vice President Pence breaking the tie.

The health-care debate is likely to spark a chaotic, unpredictable couple of days on Capitol Hill — with senators voting on everything from abolishing much of the law to what is being called a “skinny repeal.” The result of these ensuing votes, many think, will be far more modest changes to the ACA than the party has long advertised.

(U.S. Senate)

“The endgame is to be able to move something at the end of this process across the Senate floor that can get 50 votes and then to get into conference with the House,” said Sen. John Thune (R-S.D.), a top McConnell lieutenant.

[‘Skinny repeal’ could be the Senate’s health-care bill of last resort]

Tuesday’s proceedings were marked by high drama, including the return of Sen. John McCain (R-Ariz.) to the Capitol just 1 1/2 weeks after he underwent surgery related to his recent diagnosis of brain cancer, and Pence’s move to cast the tiebreaking vote. The intensity of the debate, including protesters who yelled “Kill the bill!” in the Senate chamber after the voting had begun, underscored the stakes involved in overhauling a health-care system that affects one-sixth of the U.S. economy and how tens of millions receive medical care.

All 48 members of the Democratic caucus voted against the procedural motion to start debate, along with two GOP centrists, Susan Collins (Maine) and Lisa Murkowski (Alaska).

Republicans have struggled mightily to get to this point, and there is no guarantee they will win final passage of the bill. In a sign of how muddled the situation remains, McCain took to the floor after voting to move ahead and declared, “I will not vote for the [BCRA] as it is today. It’s a shell of a bill right now.”

[McCain returns to Senate for health care vote to emotional applause from his colleagues]

Sen. Jerry Moran (R-Kan.) echoed these sentiments, tweeting, “I support a full repeal of Obamacare & will continue to oppose the BCRA.”

Trump has been pushing aggressively for Republicans to pass a repeal-and-replace plan, saying opposing the procedural motion to proceed with debate would be tantamount to endorsing the law known as Obamacare.

Speaking at a joint news conference in the Rose Garden on Tuesday, the president said he is “very, very sad” for the Republicans who opposed the motion but “very happy with the result” of the vote.

“Now we’re all going to sit together and try to come up with something really spectacular,” he said. “It’s a very, very complex and difficult task, something I know quite a bit about.”

Now, Senate GOP leaders plan to move ahead with votes they hope will culminate at the end of the week in the passage of at least narrow changes to the ACA that will become the basis for negotiations with the House. This “skinny repeal” strategy would keep the overhaul effort alive but amount to a tacit acknowledgment that broader efforts to revise or repeal the law cannot succeed, even as Republicans control both Congress and the White House.

“They expect us to tackle the big problems,” McConnell said on the Senate floor, referring to American voters. “So all we have to do today is to have the courage to begin the debate. . . . Let the voting take us where it will.”

At least two of the votes were largely for show, as the measures at stake were expected to be defeated. The first was on an altered version of the Senate GOP bill to repeal and replace the law, which included proposals from Sen. Ted Cruz (R-Tex.), a conservative, and Sen. Rob Portman (R-Ohio), a moderate, and was subject to a 60-vote threshold. That was defeated, 57-43, with 60 votes required for passage. Later, senators will move on to an attempt to repeal the law, which as of last week lacked enough Republican support to succeed.

The “skinny repeal” option would repeal the ACA’s mandates that individuals buy plans and that employers with 50 or more employees provide coverage, said lobbyists and Senate aides, as well as eliminate the law’s tax on medical device manufacturers.

Democrats signaled that they won’t stand in the way of plans to vote on different versions of the legislation.

“These votes, frankly, are a lot tougher for them than they are for us. They are squeezed in both directions,” Senate Minority Leader Charles E. Schumer (D-N.Y.) told reporters.

Sen. Richard J. Durbin (D-Ill.), the party’s top vote-counter, acknowledged that some Democrats might support GOP-written amendments to the bill that have bipartisan support. But he said Democrats will focus mostly on process over policy, and keep pushing Republicans to return the legislation to committee and proceed with regular procedure. There have been bipartisan complaints that the legislation was drafted — by McConnell and a handful of leaders — without enough transparency.

Recognizing their lack of leverage in the chamber, Senate Democrats decried Republicans’ policies and procedural approach in a rally with supporters outside the Capitol. “How about we fill the streets outside every Republican office in America?” said Sen. Jeff Merkley (D-Ore.).

Several patient-advocate organizations and progressive groups decried the vote, warning that it could open the door to rollbacks in the expanded coverage the ACA has provided through new benefits requirements and greater federal support for insurance coverage.

“Republican leaders are using undemocratic and unprecedented means to rob coverage and critical services from millions of women, sending them back to a time when Women’s Health Care Services were not considered essential,” Nancy Northup, president and chief executive of the Center for Reproductive Rights, said in a statement.

Meanwhile, Nathan Nascimento, vice president of the conservative group Freedom Partners, urged senators to use the votes to partly repeal the law and then keep pushing for full repeal. “And then use the next available opportunity to keep their promise by repealing the rest of Obamacare, including its costly regulations and choice-stifling mandates,” he said.

But one key way Senate leaders won Tuesday’s procedural vote was by assuring several centrist Republicans that they may end up with a modest bill.

McConnell and his deputies were still bartering with a handful of GOP holdouts in the hours leading up to the vote. Among the skeptics were about half a dozen Republicans from states that expanded their Medicaid programs under the ACA to cover able-bodied adults and low-income parents earning up to 138 percent of the federal poverty level.

Although it was clear that some, such as Collins, were unlikely to support McConnell’s repeal plan, Portman and Sen. Shelley Moore Capito (R-W.Va.) remained in talks with leaders until the final days.

The group’s members have met regularly since talks started earlier this year, and they have generally banded together to ward off conservative demands that the bill slash funding for Medicaid. The group was largely quiet in the days leading up to the vote, but Sen. John Cornyn (R-Tex.) said he thinks leaders won it over with a spate of last-minute bartering, including a pledge to include Portman’s amendment.

That provision would add $100 billion more in federal funding to help consumers with out-of-pocket medical costs, said senators and aides, and would allow states to provide cost-sharing assistance to low-income people who transition from Medicaid to buy private insurance with a federal tax credit.

“They’ve been very diligently working to make sure their concerns were addressed,” Cornyn said. “As recently as the last couple of days, they indicated they were likely willing to proceed based on the improvements to the underlying bill that they’ve been working on.”

Conservatives, meanwhile, lobbied for concessions. Senate leaders have agreed to include Cruz’s amendment in their revised plan, thereby allowing insurers to offer bare-bones health plans on the ACA market as long as they provide at least one option that meets the current law’s minimum requirements.

After McCain’s floor speech, most Senate Democrats headed down the stairs of the Capitol, where TV cameras were waiting for them. But even as they sought to rally with protesters, Republicans had put up an obstacle to their plans. Pence’s motorcade was speeding away, leaving the activists temporarily stranded on the other side of the street.

Amy Goldstein, Ed O’Keefe, David Weigel and Paige Winfield Cunningham contributed to this report.

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