Only one debater left Cleveland in a stronger position than when she arrived, and the pronoun gives away her identity: Carly Fiorina. She managed the rare trick of maintaining her dignity while demonstrating her combativeness. Whichever pundit first suggested that there might be advantages to appearing on the less contentious 5 p.m. stage rather than the 9 p.m. all-holds brawl—that pundit had a point.

The majority of the debaters leave Cleveland no worse off than they were before. But the two candidates long thought of as front-runners look seriously worse today than yesterday: Jeb Bush and Scott Walker.

Donald Trump was riding high before the debate and continues to ride high now; Jim Gilmore and George Pataki had nowhere to go but up; for John Kasich, simply making it onto the 9 p.m. stage counted as a victory; and Rand Paul and Chris Christie face campaign problems that are so serious that one bad night at a debate doesn’t make a difference.

A few candidates return home bruised, but for now unbloodied. Even Ben Carson’s most fervent admirers must wonder today whether politics really is the right field for his talents. Marco Rubio—who generally showed to advantage last night—was pushed to take a position on granting exceptions in the cases of rape, incest, and danger to the life of the mother to a hypothetical abortion ban. He seemed to suggest that he was opposed to such exceptions—the right answer for a Republican primary, apparently, but the wrong answer for a general election.

For Walker and Bush, though, the evening was a disappointment. Both men planned their debate on the assumption that it was more important to survive than to win. Jeb Bush, after all, is the heavy favorite among the Republican Party’s big donors, a group that usually gets its way. Scott Walker has positioned himself as the single candidate least unacceptable to all major Republican factions—the kind of candidate who got picked in the era of the smoke-filled room and who still often prevails today (think Bob Dole for the Republicans in 1996, or John Kerry for the Democrats in 2004). Novelty candidates may flare from time to time, as they did in 2012, but Bush and Walker have the financial and political resources for the long march—or so they and their backers can believe.

That belief took a battering last night.

While Rubio had to be pushed toward the Todd Akin position on abortion, Walker willingly identified with it. That’s a dangerous position for the candidate whose selling point is that he’s uniquely acceptable both to ideological activists and to the electability-minded mainstream. The case for Walker is that he’s principled, if uncharismatic. The case against him is that he’s doctrinaire and unpersonable. Megyn Kelly’s question, “Are you too extreme?” gave Walker the opportunity to reveal a more nuanced, thoughtful, compassionate side. Such a self-revelation might have inspired party leaders to think, “Here’s our best back-up plan if Jeb Bush fizzles.” They now have to worry whether Walker might actually be a less-articulate and self-disciplined version of Ted Cruz.

As for Jeb Bush, he had the worst night of all. His job in these debates is to replicate Mitt Romney in 2012: to prove himself the most professional, most knowledgeable, and least-flawed choice in a big field. The activists may not like it, but as one after one of their preferred alternatives falters, they will have to submit to the reality, “Guys, there’s only one potential president on that stage.”

The essential precondition for replicating the Romney strategy is to avoid mistakes. Jeb Bush keeps stumbling into them. In May, Megyn Kelly hit Jeb Bush with the hardest—but also single most-predictable question—he faced as a candidate: Knowing what you know now, would you have supported the Iraq war in 2003? Bush famously floundered for nearly a week before at last pronouncing the answer: No. Last night, Kelly hit with the equally predictable follow-up: If Iraq was a mistake, as you now agree, what do you say to those who lost their lives in your brother’s war? Bush floundered again.

Bush’s troubles must raise two concerns in the minds of his supporters, one mildly disquieting, one extremely so.

Mildly disquieting: If a candidate can’t cope well with the predictable hard questions, how will he cope with the unpredictable hard questions?

Extremely disquieting: Doesn’t a Jeb Bush nomination inevitably reframe the 2016 election as a referendum on George W. Bush’s legacy, Iraq and all? (I should mention: I worked as a speechwriter in the administration of Jeb Bush’s brother; my wife has donated to Walker’s SuperPAC.) Jeb Bush may answer that he is his “own man,” but doesn’t his mere presence guarantee that questions will continually be asked about decisions made a decade ago and more—and doesn’t he have less freedom to find new answers than any one else on either the 9 p.m. or 5 p.m. stage?

Neither Walker nor Bush committed a fatal error last night. But they lent credence to doubts that can only grow. It may be that while their campaigns are designed for the long haul, the inherent difficulties of their candidacies will prove even more enduring.