Every other candidate is going somewhere very soon. For all but one, or at most two, of those candidates, that somewhere is down. In a sense, the encounter at St. Anselm College in Manchester, aired nationally by ABC News, had only one question: This is a race between Sanders and BLANK.

All six others on the stage had some very effective moments; all six also came out of the debate with questions about their durability still hovering.

Two candidates in particular, former South Bend, Ind., Mayor Pete Buttigieg and Sen. Amy Klobuchar, gave performances that conveyed ascendancy.

In Buttigieg’s case, that was aided by his effective tie with Sanders in the Iowa caucuses and polls indicating high prospects for another good performance in New Hampshire on Feb. 11. He was often crisp and commanding, with a glaring exception. The question on which he most need to be strong, his own record on racial justice, was where he was weak and had this weakness rubbed in by other candidates.

In Klobuchar’s case, she delivered what may have been her most effective debate outing so far. People often assume artifice in politicians. But she seemed quite sincere in her irritation with Buttigieg, needling him about his inexperience and what she described as his glib dismissal of people who are getting things done in Washington in his desire to come off as a “cool newcomer.” She also gave an impassioned appeal for racial justice, the key to which she said is halting Republican efforts to dilute the African American vote through gerrymandering and voter purges.

The question for her, of course, is how much time she has left to make a credible claim to be the leading alternative to Sanders.

Both Buttigieg and Klobuchar need the same thing to happen: Another weak turn on Tuesday from former Vice President Joe Biden, increasing the doubts about him before he can arrive in the only early state where he is performing well: South Carolina, which votes Feb.29.

Biden had a strong performance, by the often discursive standards of his debate outings. But his strategic vulnerability was highlighted by his own confession in the opening minutes of the debate. “I took a hit in Iowa, and I will probably take a hit here,” he said. “Bernie won [New Hampshire] by 20 points last time,” referring to Sanders’ victory over Hillary Clinton in 2016.

Repeating arguments made in Iowa by his strategists, he said he regards the first four states to vote, including Nevada, as the opening phase of the contest and people will examine those contests cumulatively.

Sen. Elizabeth Warren, based on some polling and her status representing Massachusetts, on the border of New Hampshire and a place where many of its residents work, has a claim on doing well in the state. But she needs to do very well — either first or a close second — for her candidacy to have viability for much longer.

She had a couple of moments during the debate — but, alas, only a couple — that were reminders of why she once looked to be atop the race before air started to leak last fall. Asked about the future of U.S. forces in Afghanistan, she said troops must come home and cited her time listening to generals from her seat on the Senate Armed Services Committee. “The bottom line is nobody sees a solution to this war,” Warren said. “Nobody can describe what winning looks like. All they can describe is endless war.”

In addition, she was one of the candidates who schooled Buttigieg when he was asked by ABC’s Linsey Davis about why black residents of South Bend during his term were “more than four times more likely” than white residents to be arrested for marijuana possession. When he gave a generic and somewhat halting answer about drugs and incarceration generally, instead of addressing his own role specifically, Davis asked Warren, “Is that a substantial answer from Mayor Buttigieg?”

“No,” Warren answered. “You have to own up to the facts, and it's important to own up to the facts about how race permeated our justice system.” She called for an overhaul of laws to be more “race conscious.”

Apart from a handful of moments, Warren often was quiet, and seemed to recede onstage.

If anything, billionaire Tom Steyer, whose viability is tenuous and needs a big surprise soon, held the stage more prominently. He showed a force and fluency that has often eluded him, arguing that differences between the candidates were trivial and that more discussion in the party was needed about how to beat Trump and win full control of Congress. Invited by moderators, he said he was worried about Sanders’ socialism and Buttigieg’s inexperience.

Cumulatively, however, it was notable how cordial the evening was. My colleague Charlie Mahtesian said by the standards of previous election cycles the debate was “a pillow fight.” With time running so short for all candidates other than Sanders, there would seem to be abundant motives for candidates to peel back skin on rivals. New Hampshire, unlike Iowa, has not necessarily punished candidates for making sharp contrasts. Presumably, Mahtesian noted, candidates are calculating that Democratic voters are not eager to hear that in a year dominated by what they regard as an existential threat to American values in Trump.

Andrew Yang also made the stage for the debate, which was sponsored by Apple News and featured cameos by journalists from New Hampshire’s WMUR. As usual, the tieless Yang was articulate and entertaining when he spoke, which wasn’t often, and, as usual, he was persistent in pushing his signature proposal of fighting social inequality by giving each adult a universal basic income of $1,000 a month. It is notable how long Yang has lasted on debate stages and the national conversation, long after candidates with more traditional résumés have dropped out. But this latest debate and weak results from Iowa raise questions about how much longer he can stay on the stage.

For people who have watched all the Democratic debates over the past seven months, the evening couldn’t help but highlight how long this contest has been going — and how much time is running short.

For Sanders, and perhaps also for Warren, the hope is that 2020 is about the power of ideology; they have spent decades sharpening and preaching ideas that have gone from the margins of Democratic thinking to the core.

For Biden, Buttigieg, and Klobuchar, they hope 2020 is principally about biography—and specifically about life stories that will contrast most vividly and appealingly with Trump. They are offering different varieties of biographical appeal: the length and often valorous struggles of Biden’s 48-year career, the dazzle of Buttigieg’s youth and intelligence, the diligence of Klobuchar’s more conventional rise.

Biography is also the essence of former New York Mayor Mike Bloomberg’s appeal. He was not on the stage, nor will he be on the New Hampshire ballot, but with his hundreds of millions in TV ads is hoping he can on Super Tuesday grasp the not-Sanders mantle.

All of them are well aware that there’s rapidly diminishing room at the top.

