– John McCain seemed poised to be the savior of the GOP health bill when he returned to the Capitol despite a brain cancer diagnosis.

He turned out to be the executioner.

The longtime Arizona senator stunned pretty much everyone Friday by turning on his party and his president and joining two other GOP senators in voting “no” on the Republicans’ final effort to repeal the Affordable Care Act.

That killed the bill. And it also dealt what looks like a death blow to the Republican Party’s years of promises to get rid of Barack Obama’s health law, pledges that helped the GOP win control of the House, the Senate and the White House.

It was a moment burning with drama, irony and contradictions, playing out live on a tense Senate floor.

Eighty years old and in the twilight of a remarkable career, McCain lived up to his reputation as a maverick. When he walked into the well of the Senate around 1:30 a.m. and gave a thumbs-down to the legislation, there were audible gasps. Democrats briefly broke into cheers.

Majority Leader Mitch McConnell stood stone-faced. McCain had just saved the signature legislative achievement of the man who beat him for the presidency in 2008, a law the senator himself had vigorously campaigned against while seeking a sixth Senate term last year.

Friday afternoon, McCain’s office announced he was returning to Arizona to begin radiation and chemotherapy treatments for his brain tumor.

After so many years as a senator, with so little left to lose, McCain had taken a stand for the Senate he used to inhabit, the one where he made deals across the aisle with the likes of Ted Kennedy, not the riven, stalemated Congress of today.

“The vote last night presents the Senate with an opportunity to start fresh,” McCain said in a statement.

President Donald Trump tweeted his disapproval of McCain’s “no” vote, as well as those of fellow GOP Sens. Susan Collins of Maine and Lisa Murkowski of Alaska whose opposition had been expected. But a president who once mocked McCain’s years as a prisoner of war in Vietnam did not have much sway with the senator when it counted.