Republican senators voted Tuesday to open debate on revising U.S. health care law, advancing a signature campaign pledge following a tense and dramatic week on Capitol Hill. But the party voted to do so only with the barest of margins, an illustration of the challenges ahead as leaders look to unite a divided and unruly caucus.

Johnny Isakson and David Perdue, Georgia’s two GOP senators, provided two much-needed votes for Senate Majority Leader Mitch McConnell, who had worked furiously over the last several days to secure the required GOP votes to kick off debate on repealing Obamacare. The final vote of the full senate was 51-50 after Vice President Mike Pence broke the tie.

Tuesday's action kicks off days of debate on the Senate floor, but the road ahead for the GOP's years-long effort to nullify the 2010 health care law is murky. There are still deep divides among Republicans about which versions of repeal or replace are politically acceptable, particularly regarding Medicaid. And it's unclear if 50 GOP senators can agree on any single proposal.

McConnell has discussed voting on several different proposals in the days ahead, including the Senate's Obamacare replacement bill. The chamber on Tuesday evening rejected a version of that plan that would also allow the sale of cheap, bare-bones insurance plans. It's on track to vote today on a proposal would erase much of the Affordable Care Act and give Congress two years to settle on a replacement.

“We can’t let this moment slip by,” McConnell, R-Ky., told his Republican colleagues ahead of Tuesday’s vote. “We talked about this too long … the people who sent us here expect us to begin this debate.”

Democrats have indicated they will sit out of this legislative fight.

“Turn back,” Chuck Schumer of New York, the Senate Democratic leader, warned Republicans in a floor speech. “We can work with you. We know that the (Affordable Care Act) isn’t perfect, but we also know what you’ve proposed is much worse.”

Quiet nail-biter

The hours leading up to Tuesday’s vote were shrouded in mystery as party leaders worked overtime to win over skeptical moderates worried about constituents losing insurance coverage and conservatives concerned that not enough Obamacare regulations were being repealed. Roughly a dozen senators had previously expressed reservations about the Senate’s repeal effort.

Susan Collins, a Maine moderate, had made clear she would not support even opening debate, so McConnell and his deputies only had one more vote to spare. When Republicans huddled for their regular weekly lunch with Pence on Tuesday afternoon, McConnell pleaded with wavering senators to at least vote to begin debate on the issue. They were also under mounting pressure from President Donald Trump.

GOP lawmakers emerged from that meeting uncharacteristically quiet, quickly filing into the Senate chamber.

Senators sat quietly behind their desks — another unusual sight for the talkative, chummy chamber — as McConnell and Schumer delivered impassioned speeches for and against the bill. Perdue looked on from his seat at the back of the chamber and Isakson with his cane resting in his lap, even as two dozen protesters erupted into chants of “kill the bill” and “shame” when McConnell opened up the issue for a vote.

Perdue and Isakson’s votes Tuesday were never seen as in doubt.

“I’m pleased,” Perdue said following the vote. “We got the first step. Now we’ve got to get to the hard work and get this thing across the line.”

The win was made possible by Arizona Sen. John McCain, who flew in just days after brain surgery combating cancer, and soon after gave an impassioned speech on comity from the well of the Senate, with a dark red scar across his left eyebrow.

Even as the former presidential candidate voted to advance the health care debate, he urged his fellow senators to work together in a bipartisan fashion and to stop heeding polarizing messages.

McCain Speaks About The Health Care Bill On Senate Floor

Meanwhile, Health and Human Services Secretary Tom Price inconspicuously watched senators cast their votes from a perch at the back of the room.

Georgia stakeholders

At the offices of the left-leaning patient advocacy group Georgians for a Healthy Future, the handful of employees gathered in outreach director Laura Colbert’s office to watch the C-SPAN livestream of the Senate vote on her computer.

“We’re incredibly disappointed that both Senators Isakson and Perdue voted to open debate on the senate health care bills,” Colbert said.

“It was very intense,” Colbert said. “This has been a really intense period and a long fight. So I think we had some hope that we might have a resolution today and we could really begin a more deliberative and constructive policymaking process. So it is disappointing that we’re not there yet.”

Colbert was concerned at the haphazard way that legislation is being considered. “It’s a really sad day in Georgia for people who need health care or will need health care,” she said. “Right now, I think we’re in dangerous territory.”

Kelly McCutchen of the free-market Georgia Public Policy Foundation also thinks we’re still in dangerous territory – but danger of doing nothing.

“I’d like to see a bill, some kind of bill, get passed to conference committee,” McCutchen said. “As a Georgian, I’d like to see us have an opportunity to have something we could work with get to the bottom of some of the issues in health care: uncompensated care, preexisting conditions and equitable tax treatment for everyone.”

“I think they’re very close in a lot of ways,” McCutchen added.

Senate debate

McConnell’s strategy for the upcoming health care debate was still unclear as of Tuesday evening.

The Senate replacement bill, as written, is deeply unpopular, according to recent polls, and currently does not appear to have enough support among Republican senators. Neither do most of the other Republican proposals.

A fallback option floated Tuesday would eliminate Obamacare’s employer and individual mandates but leave many other portions of the 2010 law in place, including the Medicaid expansion, which has become popular with some GOP governors.

Georgia did not choose to expand Medicaid under the law, citing the financial burden.

Moderates are seeking more money for the 31 states that did expand the entitlement and would be hurt by the proposed cuts to the program in the Senate bill.

Perdue has indicated he’s on board with the Senate replacement plan and even with the repeal-only proposal. Isakson previously sent positive signals about the former but in January spoke out against tearing down the 2010 law without a replacement ready.

Isakson was non-committal about the repeal-only concept on Tuesday.

“I’m going to support what I think is right, which is what I always do,” he said. “Nobody knows until we see it.”