NEW YORK (CBSNewYork/AP) — Sen. John McCain says he won’t vote for the Republican bill repealing the Obama health care law.

His statement likely deals a fatal blow to the last-gasp GOP measure in a Senate showdown expected next week.

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The Arizona Republican says he can’t back the Graham-Cassidy bill, because “we could do better working together, Republicans and Democrats.”

He also says he can’t back it without knowing the proposal’s impact on insurance coverage and premiums. The nonpartisan Congressional Budget Office has said its estimates on that won’t be ready next week.

Kentucky Sen. Rand Paul has said he’ll oppose the bill and Maine Sen. Susan Collins says she’s leaning against it. McCain says three other senators may also vote “no.”

Congressman Peter King, who also opposes the bill, said he admires McCain’s decision.

“John McCain has always been heroic. You can’t plan on what John McCain is going to do, he’s his own man,” King said. “I didn’t expect it, but I’m not surprised.”

For his part, Sen. Lindsey Graham has no hard feelings toward McCain. He tweeted, “My friendship with Sen. John McCain is not based on how he votes but how he’s lived his life and the person he is.”

McCain’s vote comes as he continues to fight a devastating diagnosis of his own. He is suffering from a deadly form of brain cancer, but has continued to work. He recently sat down with “60 Minutes” to discuss his health.

In the interview that will air Sunday, he tells Lesley Stahl how his diagnosis unfolded. While on his way home from a checkup in July, his doctor called him back into the office.

“I was driving up here and I got about up two thirds of the way up, and my doctor called and said, ‘You have to come back.’ And I said, ‘Hey, today is Friday. I’ll just come in Monday.’ And she said, ‘No, you have to come now. It’s very serious,'” he says.

He turned the car around and immediately went into surgery.

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“They felt it was serious enough that they had to act immediately,” he says.

McCain told Stahl he urged his doctors to tell him the truth about his glioblastoma.

“I kept saying to them, ‘tell it to me straight.’ Well there’s always this, there’s always that. I said, ‘I can take it, just tell me.’ And then they were more forthcoming,” he says.

If the new bill is passed, Democratic Sen. Bob Menendez said 900,000 New Jerseyans would lose coverage.

“The latest Republican plan still asks families to pay more for less,” Menendez said.

“My life was saved by Obamacare,” said New Jersey resident Jean Scully, who has had a series of cascading medical problems that have been covered by insurance. “My medical bills just since Jan. 1 of this year have so far been $76,000.”

Ali Chandra, of New Jersey, understands what’s at stake. When she was 25 weeks pregnant doctors told Chandra that her son had nine critical congenital heart defects, two left lungs, five spleens, and a stomach on the right side.

“Medicaid paid for Ethan’s birth, his first two surgeries,” she said.

Her son, who is now three years old, has already had five heart surgeries and Obamacare ensures her private insurance will cover the bills.

Republicans control the Senate 52-48.

All Democrats oppose the bill so three GOP “no” votes would doom it.

“I think what John McCain did today basically ended the bill. And we have to go forward after October 1st and try to find a bipartisan way to reform and improve Obamacare,” King said.

This is the second time McCain has voted against a repeal of Obamacare, the last time in July right after his diagnosis.

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(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)