There’s never any one reason that presidential campaigns end. Well, actually, there is, and Kamala Harris acknowledged it in her statement: Money. She was running out of it. It sucks, but it’s life.

Beyond that, though, post-mortems can point to a range of reasons. She never developed a clear rationale. Her campaign was a mess. Her prosecutor background was a killer among the woke. They’re all true to one extent or another. I remember thinking during her announcement speech that while it was obviously really impressively staged and she had a ton of personality, she didn’t seem to have much to say about economics.

At a time when one of the core issues facing this country, or probably the core issue, is the various crises born of this malignant form of capitalism we’re living under, and when Democrats are desperate for action on inequality and the class war being waged against working people and young people, Harris’ economic world view was never really clear.

But I want to emphasize another point. I’m not saying that this particular factor was decisive for Harris. It probably was not. But it definitely tripped her up. And it’s worth taking note: If you combine Harris and Elizabeth Warren, that makes two campaigns that lost a lot of steam because of Medicare for All.

It was at a CNN town hall in January that Harris wrapped her arms around M4A. An audience member asked her about it. You can see the clip here. Then Jake Tapper followed up with the inevitable do-you-mean-that-private-insurance-would-be-eliminated question, and she said yes to that, too.

She spent the next six months or so campaigning on basically that position—endorsing Bernie Sanders’ bill, which clearly calls for the elimination of private insurance. Then came that first debate (held over two nights) and the famous moment when Lester Holt asked the candidates if they’d eliminate private insurance. Warren and Bill de Blasio raised their hands the first night. Harris and Sanders raised their hands the second.

Harris started backpedaling from that position literally right after the debate. She told an NBC reporter, “Medicare for All—in my vision of Medicare for All, it includes private insurance where people can have supplemental insurance.” She said much the same on Morning Joe the next day.

And she essentially spent all her time since late June trying to explain what her position really was. She acknowledged to The Washington Post in late August that she’d boxed herself in: “I don’t think it was any secret that I was not entirely comfortable—that’s an understatement,” Harris told the paper. “I finally was like, ‘I can’t make this circle fit into a square.’ I said: ‘We’re going to take hits. People are going to say she’s waffling. It’s going to be awful.’”

Warren’s contortions followed a similar path, with of course one big difference. Whereas Harris backed off M4A in the immediate aftermath of that first debate, Warren decided she was in for a penny, in for a pound. She stuck with it, reasoning that the hits she’d take for flipping would be worse than the hits she’d take for embracing the near-immediate end of an insurance system that two-thirds of Americans depend on.

I thought at the time that Warren made the right call and Harris the wrong one. Better to take the hits. But it turned out that both positions were untenable. People started asking Warren “where’s your plan?” and it was delayed and delayed, and then finally she released it—and then, after it opened to mixed reviews at best, within a few weeks, she backed off it.

Now, one could say here, “Well, they both screwed up by backing away. They should have stood their ground. They’d have come across as principled.” Maybe. But Warren tried principled. For a long time. And the general arc of her career tells us that she is not an unprincipled person. And yet, something made her change.

What that something was is pretty obvious. There will be $500 million worth of right-wing attacks. Maybe more. They’ll be exaggerated. They’ll be vicious. But they’ll be hard to rebut.

For the nth time, I’m on the record saying we should move toward M4A (though not necessarily Sanders’ exact version), but in stages. It was obvious from jump street that Warren and Harris were going to run into these problems. Read my post-debate column, after that first June debate, in which I wrote, “Having just won a historic victory in the 2018 election on health care, the Democrats now seem hellbent on trying to lose the 2020 election on the same issue.” And I was hardly alone.

Harris was impressive in many ways. I’m saddened by her abrupt departure. I wanted to see how she did when people started voting. I thought maybe she had a second wind in her. As it is, she made her mark. If Joe Biden becomes the nominee, she’s a pretty obvious choice to be his running mate. And if they win, there seems a decent chance that Biden serves only one term, and then… In any case, she’ll be a force in the party for 30 years.

I’m not saying M4A brought down her campaign. But I can’t help but wonder how she’d be doing now if she’d just embraced a Medicare buy-in position from the start. And here’s hoping that if she runs again, she’s learned the lesson that positions that get big applause from very liberal audiences two years out from the election don’t always wear well.