Consider the “Jimmy Kimmel test.” That’s what Bill Cassidy, the Republican Louisiana senator, said in May that he would use to judge any proposal, in honor of the talk-show host whose newborn son needed heart surgery. Cassidy said he wanted to ensure “a child born with a congenital heart disease be able to get everything she or he would need in that first year of life.”

Cassidy, though, has now put his name on a bill that would harm such a child (because insurers could hike the family’s rates after the diagnosis). He has recanted, without acknowledging it.

For the bill to pass, McCain would probably also need to reverse himself. Any three Republicans can stop the bill, and he — along with Susan Collins, Lisa Murkowski, Rand Paul, Jerry Moran, Lamar Alexander and a few others — is one of the swing votes.

There is reason to believe McCain will stand firm, starting with his sense of personal honor. It’s hard to imagine him violating it to help a president who personally demeaned him. But McCain showed worrisome signs of wobbling Monday, saying he may “reluctantly” support the bill. He also listens to Arizona’s governor, Doug Ducey, who endorsed the bill even though it could nearly double the state’s uninsured population.

No doubt, the White House and other senators are concocting rationales — like a single hearing next Tuesday — for why a yes vote by McCain would not violate his principles. But that’s laughable. Graham-Cassidy has followed the hasty, secretive, partisan process that McCain so eloquently decried.

The good news is that McCain has leverage. The compromise that he wants — that both sides “criticize but also accept” — is entirely feasible. Democrats want to fix Obamacare’s problems, both for substantive reasons and to avoid a civil war over a single-payer system. The outlines of a deal, with more state flexibility but without coverage losses, are obvious.

John McCain is a complicated figure. One of his own aides recently described him as “nine parts hero, one part troll.” He has strengths and weaknesses, as the rest of us do, and I won’t pretend to agree with all of his opinions. But he has, undeniably, made greater sacrifice for this country than most of us ever will.

It would be a tragedy for the country if he were now willing to take away decent health care from millions of people. It would be a tragedy for him if he went back on his word so blatantly. I remain hopeful that he will stay true to it.