(CNN) Sen. John McCain announced Friday in a statement that he cannot "in good conscience" vote for the GOP's latest plan to overhaul Obamacare, likely ending Republicans' latest effort to repeal and replace the Affordable Care Act. 
 
 "I cannot in good conscience vote for the Graham-Cassidy proposal," the Arizona Republican said in a statement. "I believe we could do better working together, Republicans and Democrats, and have not yet really tried. 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. Without a full CBO score, which won't be available by the end of the month, we won't have reliable answers to any of those questions." 
 
 McCain's "no" vote means it is likely Republicans won't be able to repeal and replace Obamacare before September 30, as Sen. Rand Paul of Kentucky said he would not back Graham-Cassidy and Sen. Susan Collins of Maine has said she is leaning "no" on the proposal. But there are still questions as to where Alaska Sen. Lisa Murkowski is at the moment. It's also unclear if senators on the fence would support a procedural motion on the bill even if they decide they are against Graham-Cassidy in the end. 
 
 Republicans need at least 50 votes to pass the measure under the process of reconciliation. 
 
 Murkowski, Paul and Collins also under scrutiny 
 
 McCain was one of three most-watched members on the fence and considered a key vote on the bill. Without his support, Republicans would need to get Murkowski as well as Collins to sign on. It's unlikely considering the fact that Collins said Friday afternoon that she was leaning against the bill and had key concerns that the legislation did not do enough to protect individuals with pre-existing conditions. 
 
 "I'm leaning against the bill," Collins said Friday at a Portland, Maine, event, according to The Portland Press Herald. 
 
 A Republican aide involved in the process said Friday afternoon that GOP leaders are at the "evaluating options" stage right now. 
 
 The aide added, "I'm not breaking news telling you this isn't good." 
 
 Paul, the only other Republican other than McCain who has so far definitively come out against Graham-Cassidy, is "unlikely" to change his mind even if changes are made to the bill, his spokesman Sergio Gor told CNN. 
 
 Graham and McCain's close friendship 
 
 McCain's announcement comes despite that one of the bill's key sponsors -- Sen. Lindsey Graham of South Carolina -- is a close confidant. The thinking was if anyone could convince McCain to vote "yes," it would be Graham. 
 
 "I take no pleasure in announcing my opposition. Far from it," McCain said. "The bill's authors are my dear friends, and I think the world of them. I know they are acting consistently with their beliefs and sense of what is best for the country. So am I." 
 
 McCain has said for weeks that he would not support health care legislation that had not gone through "regular order," meaning Senate hearings, an amendment process and a rigorous floor debate. 
 
 Graham said he "respectfully" disagrees with McCain and will "press on" with his legislation. 
 
 "My friendship with John McCain is not based on how he votes but respect for how he's lived his life and the person he is," Graham said in a statement and on Twitter, adding later, "I feel an obligation to fix this disaster and intend to push forward for state-centric health care versus Washington-knows-best health care." 
 
 My friendship with @SenJohnMcCain is not based on how he votes but respect for how he's lived his life and the person he is. — Lindsey Graham (@LindseyGrahamSC) September 22, 2017 
 
 McCain voted "no" on the last health care proposal in July for the same reason. McCain's dramatic floor vote, which happened just weeks after he was diagnosed with brain cancer, came in the early morning and was captured as one of his most "maverick" moments in the Senate. 
 
 What the White House is thinking 
 
 A senior White House official told CNN that McCain's opposition "undeniably hurts" the effort to repeal and replace Obamacare but that President Donald Trump is not ready to give up on the effort yet. 
 
 "The President has been engaged all along, and I think you will continue to see him reach out," the official said. "We have been having conversations with Graham and Cassidy for a couple months and ... even though there may be members who want to give up, the President does not." 
 
 Top White House aides have been talking with Graham and Sen. Bill Cassidy for months now, and in between events at the United Nations this week, Trump called senators to talk about the upcoming health care vote, White House officials said. Trump was hoping to solidify Republicans around the deal struck by the two senators and urged many of the lawmakers to stay loyal to him. 
 
 The White House official, though, added that even though chances of passing health care look bleak, the White House intends to juggle between Graham-Cassidy and tax reform next week. 
 
 Vice President Mike Pence indirectly addressed the decision during a speech Friday afternoon in Anderson, Indiana. 
 
 "The vote could come as early as next week and this is not going to be easy. Even now, the opposition is forming up and some have gone so far to announce their opposition already. But President Trump and I are undeterred," Pence said. 
 
 "We cannot in good conscious abandon this cause," Pence said to applause in his home state. 
 
 Democrats praise McCain 
 
 Just moments after McCain announced his opposition, Democrats seized on the opportunity to bring back bipartisan talks that had stalled last week. 
 
 Democratic Sen. Patty Murray of Washington and Republican Sen. Lamar Alexander of Tennessee had held bipartisan hearings over the last month on how to stabilize Obamacare marketplaces and were making progress in their negotiations. But the House leadership made it clear last week that the chamber probably would not be able to pass such a bill. 
 
 As soon as McCain announced his opposition, Murray announced she was still open to reigniting those talks. 
 
 "I agree with Senator McCain that the right way to get things done in the Senate — especially on an issue as important to families as their health care — is through regular order and working together to find common ground," Murray said. "I'm still at the table ready to keep working, and I remain confident that we can reach a bipartisan agreement as soon as this latest partisan approach by Republican leaders is finally set aside." 
 
 Senate Minority Leader Chuck Schumer also praised McCain shortly after his announcement. 
 
 "John McCain shows the same courage in Congress that he showed when he was a naval aviator," the New York Democrat said in a statement. "I have assured Senator McCain that as soon as repeal is off the table, we Democrats are intent on resuming the bipartisan process." 
 
 For her part, House Minority Leader Nancy Pelosi said her members would continue working "to put the stake in the heart of this monstrous bill." 
 
 "This weekend, we will continue to highlight the devastating costs Republicans are trying to inflict on hard-working Americans," she said in a letter to colleagues. 
 
 This story has been updated and will update with additional developments. ||||| Graham-Cassidy Health Care Hearing Starts With Eruption Of Protests 
 
 Updated at 6:20 p.m. ET 
 
 Republican Sens. Lindsey Graham of South Carolina and Bill Cassidy of Louisiana defended their namesake health care bill Monday even as the measure ran into potentially fatal opposition from a third Senate colleague. 
 
 Sen. Susan Collins, R-Maine, came out against the bill, joining fellow Republicans Rand Paul of Kentucky and John McCain of Arizona. That leaves the GOP majority at least one vote short of the 50 votes needed to pass the bill over unified Democratic opposition. 
 
 Collins' announcement came after the nonpartisan Congressional Budget Office released an analysis saying the bill would leave millions more Americans without comprehensive insurance. The CBO did not have time to provide a precise estimate. CBO forecasts of a spike in the number of uninsured people were a factor in the defeat of earlier Obamacare repeal efforts. 
 
 Separately, researchers at the Brookings Institution predicted the Graham-Cassidy bill would leave 32 million more Americans without health insurance by 2027. 
 
 The research firm S&P; Global also predicted the bill would leave more people uninsured, cost 580,000 jobs over the next decade, and be a drag on U.S. economic growth. 
 
 Monday's hearing was immediately interrupted by protesters chanting, "No cuts to Medicaid. Save our liberty." 
 
 Enlarge this image toggle caption Saul Loeb/AFP/Getty Images Saul Loeb/AFP/Getty Images 
 
 Committee Chairman Orrin Hatch, R-Utah, suspended the hearing for about 15 minutes while the demonstrators — some in wheelchairs — were dragged from the room. 
 
 "If the hearing is going to devolve into a sideshow or a forum for simply putting partisan points on the board, there's absolutely no reason for us to be here," Hatch said. 
 
 The bill's authors made changes to the legislation in hopes of winning over holdouts, but that effort appeared to be in vain. 
 
 Oregon Sen. Ron Wyden, the ranking Democrat on the committee, complained that Republicans are trying to push through an inadequate bill to beat a deadline Saturday and avoid a Democratic filibuster. 
 
 "Nobody has got to buy a lemon just because it's the last car on the lot," Wyden said. 
 
 The bill would eliminate federally financed subsidies for people buying insurance on the individual market as well as the Medicaid expansion. Some of that federal money would be repackaged as block grants for the states. 
 
 "My goal is to get the money and power out of Washington, closer to where people live, so they'll have a voice about the most important thing in their life," Graham said. 
 
 The bill would also make major changes to traditional Medicaid, capping the federal government's contribution. Over time, federal expenditures on Medicaid could grow more slowly than health care costs, shifting responsibility for those bills to state governments or patients themselves. 
 
 Graham argued that unless Congress is able to put the brakes on health care spending, it will consume an ever growing portion of the federal budget. 
 
 The acting secretary of Pennsylvania's Department of Human Services said she welcomes flexibility, but not if it comes with a smaller budget. 
 
 "Cutting billions of dollars from Medicaid and giving states reduced funding in the form of block grants — funding that goes away after seven years — is not the kind of flexibility that we're looking for," said Teresa Miller. 
 
 She added such cuts would force governors to make agonizing choices. 
 
 "Who should receive health care?" Miller asked. "A child born with a disability? A young adult struggling with an opioid addiction? A mom fighting breast cancer? A senior who's worked hard all his life and needs access to quality health care to age with dignity?" 
 
 The bill would eliminate the requirement that most Americans obtain health insurance or pay a penalty. It would also allow states to ease restrictions on the insurance market, which critics say would lead to higher prices for people with pre-existing medical conditions. 
 
 Enlarge this image toggle caption Saul Loeb/AFP/Getty Images Saul Loeb/AFP/Getty Images 
 
 "This bill is an all-out assault on vital consumer protections," Wyden said. "It's going to make the health care that many people need unaffordable." 
 
 He pointed to the wide variety of industry and consumer groups that have come out against the Graham-Cassidy bill, including the American Medical Association, America's Health Insurance Plans and AARP. 
 
 "You managed to bring together people and organizations in the health care field who rarely agree," Wyden told Cassidy. "I guess congratulations are in order because they all think what you're talking about is a disaster." 
 
 More than 200 protesters had lined up outside the hearing room hours before it started — many arrived as early as 6 a.m. 
 
 "If Medicaid is cut so dramatically, it will force people into institutions," said Bruce Darling, an organizer from New York with the disability rights group ADAPT, ahead of the hearing. "For people with disabilities, Medicaid is our life and our liberty," he added. 
 
 NPR producer Barbara Sprunt contributed to this report.
– The latest Republican effort to repeal the Affordable Care Act may very well be dead after Sen. John McCain announced his opposition to it Friday, the AP reports. "I cannot in good conscience vote for the Graham-Cassidy proposal," CNN quotes McCain as saying in a statement. "I believe we could do better working together, Republicans and Democrats, and have not yet really tried." This would be the second time McCain has put a nail in the coffin of Republican efforts to end ObamaCare. McCain said he couldn't vote for the Graham-Cassidy bill without a CBO score, which wouldn't be available until later this month, to let him know "how much it will cost, how it will affect insurance premiums, and how many people will be helped or hurt by it." Republicans could only afford to have two senators side with Democrats in opposition to the bill. Sen. Rand Paul was already opposed and Sen. Susan Collins was leaning that way. A recent poll found only 24% of Americans support the Graham-Cassidy bill and 50% disapprove of it, the Hill reports.