The Obamacare repeal zombie rose yet again this week for its last, best chance to gut the current health law — until the Republican senator who put it down in July returned on Friday to deliver another conclusive blow.

This time, it seems, it's over. Maybe. Probably. Almost definitely.

Arizona Sen. John McCain released a statement Friday afternoon confirming he will vote No on the Graham-Cassidy health bill, a resurrected effort to dismantle the Affordable Care Act (ACA), also known as Obamacare.

His decision to oppose the repeal bill appears to be the third by a Republican — after McCain's Senate colleagues Susan Collins and Rand Paul also expressed their resistance — to cut the last-gasp effort at Trumpcare.

Obamacare opponents can only afford to lose two Republican votes due to their slim majority in the Senate.

I cannot in good conscience vote for Graham-Cassidy. A bill impacting so many lives deserves a bipartisan approach. <a href="https://t.co/2sDjhw6Era">https://t.co/2sDjhw6Era</a> <a href="https://t.co/30OWezQpLg">pic.twitter.com/30OWezQpLg</a> —@SenJohnMcCain

"I believe we could do better working together, Republicans and Democrats, and have not yet really tried," McCain said in a statement. "Nor could I support it without knowing how much it will cost, how it will affect insurance premiums, and how many people will be helped or hurt by it."

McCain waffled on whether to support this iteration due to the lack of debate, hearings and revisions that comprise the deliberative process known as "regular order" in Congress. On Friday, he finally said he "cannot in good conscience" support the proposal without a full analysis from the Congressional Budget Office.

The nonpartisan CBO did not have time, given the haste to jam the bill through for a vote before the end of a crucial Sept. 30 deadline, to calculate costs and insurance losses.

The roll call scheduled for next week seemed somewhat improbable in the first place, though it unexpectedly gained steam quickly. The previously under-the-radar proposal sponsored by South Carolina's Lindsey Graham and Louisiana's Bill Cassidy was sold as the only viable repeal-and-replace plan to overhaul Obamacare.

Three Republicans, Sen. Lindsey Graham of South Carolina, Sen. Bill Cassidy of Louisiana and Senate majority leader Mitch McConnell of Kentucky, left to right, hold a news conference Tuesday to drum up coverage of the health care bill. (Alex Brandon/Associated Press)

Opponents of the repeal argued it could deny health coverage to tens of millions of Americans. Graham-Cassidy was widely seen as introducing the most drastic changes yet to the health law.

"This bill is at the very least as bad, or likely worse" than its predecessors, said Edwin Park, health-reform expert with the Center on Budget and Policy Priorities.

In broad terms, Graham-Cassidy would make the most far-reaching changes of any proposals so far, dismantling major parts of Obamacare. The bill proposes to eliminate:

Subsidies that help people afford insurance via tax credits.

Obamacare's "individual mandate," which required most people to have insurance or pay a penalty.

Expansion of Medicaid, the program that covers about 70 million low-income people.

Consumer protections for people with "essential" treatment needs.

Regulations that restrict insurers from charging higher premiums to people with pre-existing conditions.

Graham-Cassidy proposes to roll the federal funding for those programs into "block grants" and distribute the money to states to set up their own systems. The bill's co-authors pitched this as "flexibility."

In theory, the primarily liberal states that prefer Obamacare — such as New York, California and Oregon — should be able to duplicate those provisions under Graham-Cassidy.

"That's the claim: If they want to, they can maintain it," Park said.

"But the block grants moves money away from states that most successfully expanded coverage through the ACA" with some cuts by as much as 50 to 60 per cent from what they would otherwise receive under the current health law, he said.

Experts argue that under this funding structure, states like Florida and Kentucky, which successfully enrolled a lot of people under Obamacare, would have seen those billions in tax credits get redistributed to, say, Alabama or Georgia.

As states that expanded Medicaid would also get reduced funding, Obamacare success stories would not be able to afford to preserve the ACA.

Jimmy Kimmel's withering attacks this week have transformed the debate over the latest Republican health-care bill and illustrated how thoroughly late-night talk shows have become homes for potent points of view. (Jimmy Kimmel Live/YouTube)

The Graham-Cassidy proposal brought to a boil an achingly personal battle for late-night TV host Jimmy Kimmel. The comedian became an unexpected political lightning rod after he said the bill's co-author, Cassidy, "lied right to my face."

On the show, Kimmel said Cassidy pledged that a future health-care bill that would have to include "no discrimination based on pre-existing conditions, lower premiums for middle-class families and no lifetime caps."

An emotional Kimmel pleaded for the guarantees after revealing his newborn son, Billy, had a congenital heart defect. Cassidy had earlier announced to Kimmel that any future plan must pass "the Jimmy Kimmel Test."

This week, the comic argued Billy would have been afforded no such protections due to his heart condition.

"Stop using my name," Kimmel blasted during one of his monologues on Jimmy Kimmel Live!

Cassidy accused the host of not understanding the intricacies of the proposal.

Following news of McCain's likely vote on Friday, Kimmel expressed his appreciation on Twitter: "Thank you @SenJohnMcCain for being a hero again and again and now AGAIN," he wrote.

Thank you <a href="https://twitter.com/SenJohnMcCain">@SenJohnMcCain</a> for being a hero again and again and now AGAIN —@jimmykimmel

Republicans tried four times this summer to pass a repeal bill. Lawmakers thought health-care overhaul was as good as dead in July. At the time, it was also McCain who snuffed out the last proposal with a dramatic and decisive thumbs-down swing vote at 1:30 a.m.

That Senate Majority Leader Mitch McConnell had scheduled a vote had suggested some confidence that Republicans could clinch it with 50 votes, plus one tiebreaker from Republican Vice-President Mike Pence.

McCain, left, and Graham wait to speak during a news conference on Capitol Hill in 2016. The longtime friends disagree on repealing Obamacare. (Susan Walsh/Associated Press)

But with at least three likely Republican No votes now, it's uncertain whether McConnell will bother to put the vote to the floor of the Senate next week, as planned.

The crucial deadline is Sept. 30, meaning the window for passage of repeal under special rules known as "reconciliation" is closing fast. After September, repeal becomes vanishingly difficult. A new budget year beginning in October hits reset on the threshold of 50 votes and raises it back up to 60.

McCain's longtime friendship with Graham, the other primary co-author of the bill, was seen as a possible factor that could influence his decision.

"But as much as he was friends with Graham and Cassidy, he couldn't bring himself to vote for it. He put policy over friendship," said Robert Laszewski, a health consultant generally critical of Obamacare. "It's what a senator is supposed to do, so good for him."

Graham tweeted later that his friendship with McCain is not based on his voting record, "but respect for how he's lived in his life and the person he is."