For a few beautiful moments last week, it looked like it might be easy.

Riding a wave of working-class support, Bernie Sanders had swept the Nevada caucuses and surged to the lead in national polls. As Democratic pundits and party leaders panicked, anti-Sanders forces were hopelessly divided between at least three unacceptable candidates: a visibly deteriorating former vice president who had been trounced in the first three contests; an upstart small-town mayor with no appeal to nonwhite voters; and a Republican mega-billionaire, whose eerie “campaign” looked less like a run for public office than an attempted corporate buyout.

Sanders appeared ready to annihilate all three on Super Tuesday, claim a massive delegate lead, and hold a commanding position in the race ahead, even if the so-called “moderates” could finally consolidate around one candidate.

Today, the baseless fabric of this vision has dissolved, leaving only the grim spectacle of Joe Biden, the new Democratic front-runner, ascending the stage in Los Angeles and confusing his wife with his sister.

There is no use in sugarcoating the scale of last night’s defeat. “Accurate intelligence of the enemy,” as Perry Anderson has written, “is worth more than bulletins to boost doubtful morale. A resistance that dispenses with consolations is always stronger than one which relies on them.”

In less than seventy-two hours, Sanders has gone from clear favorite to anxious underdog. Once the favorite to win ten or more contests, Sanders claimed just five; once hoping to land knockout blows in Minnesota and Massachusetts, Sanders absorbed haymaker defeats in both states; once hoping to hold a 200-delegate lead after last night’s ballots, he now appears likely to trail Biden by something like 75 delegates, even after all the California results are reported.

The timely withdrawals of Pete Buttigieg and Amy Klobuchar gave Biden a massive boost in momentum, helping him score blowout victories in Virginia and North Carolina, where polls showed a close race just days before. Elizabeth Warren, who remained in the race despite finishing behind Buttigieg in the first four states, did not give Sanders any countervailing support.

Much about this year’s race has changed from 2016, including Sanders winning massive support from Latino voters. But last night, Biden succeeded in stitching together two essential elements of the coalition that Hillary Clinton used to defeat Sanders four years ago: white, college-educated voters, mostly in affluent suburbs; and black voters in the South. Both of these groups are mostly made up of older people, and Biden, like Clinton, crushed Sanders with voters over age fifty.

Can Sanders fight his way back? Biden’s delegate lead is far from insurmountable. But unless Sanders can change the essential dynamic of the race — unless he can erode the Biden coalition that emerged last night — he will struggle to compete in the states ahead, from Michigan to Florida to New York.

And yet a race that utterly changes complexion in just one seventy-two-hour period can, perhaps, utterly change complexion again. Last night, Biden was riding high on the drama of the last few days: the endorsements from Buttigieg, Klobuchar, Beto O’Rourke, and Harry Reid appear to have convinced many Democrats that a vote for Biden was a vote for safety and unity against chaos and division.

But in the weeks ahead, safety and unity will not be on the ballot, the stump, or the debate stage. Instead, voters will have to reckon with Joe Biden himself, whose own obvious vulnerabilities can no longer be obscured by the tangle of a half dozen competing candidates.

The outlines of a potential Biden-Trump campaign will come closer into view, beginning with a dismal rehash of the politics of impeachment, centering on Hunter Biden, Burisma, and Ukraine. And Democrats will have a chance to take another look at Biden’s remarkable forty-year political record of betraying American workers, from his calls for Social Security cuts to his cheerleading for NAFTA to his stalwart service to the predatory lending industry. And Biden’s own mental capacity, under question all campaign long, will be tested in ways we have not yet witnessed.

Will voters still like what they see? The next few weeks will tell — but amid the wreckage of last night, there were a few reasons to believe that Bernie Sanders can still make an alternative case that many Democrats find persuasive.

Everywhere Bernie’s signature issues were on the ballot last night, they won. Medicare For All — described as “a government plan instead of private insurance” — earned decisive Democratic support in all twelve states where it was polled, from Alabama (51 percent to 43 percent) to Texas (64 to 33 percent). Free public college tuition won even more dominant majorities in all five states it was polled.

Even “socialism” itself won landslide victories in Texas and California, a comfortable majority in North Carolina, and a plurality in Tennessee. Tens of thousands of Joe Biden Socialists, we learned last night, walk the streets of Houston, Charlotte, and Nashville.

No matter what conservative pundits may say, Democratic voters did not express any overriding fear or concern about Bernie Sanders’s agenda last night. In fact, they endorsed it, overwhelmingly. But in a primary campaign dominated from beginning to end by a desperate Democratic desire to beat Donald Trump, voters expressed a belief — perhaps durable, perhaps fleeting — that Biden is the best candidate to do that job.

Sanders faces a hard road ahead. The post-Nevada mirage has vanished: in retrospect, probably, we should never have let ourselves believe that this could be so easy. It was always going to be a fight.

Yet nor can we afford to wallow in despair. Last weekend, Democratic bosses decided almost overnight to place all their chips on Joe Biden; last night, in a frantic lunge for safety, Democratic voters followed their lead.

But in a bare-knuckled battle with Trump, does real safety belong with this candidate, whose name is a synonym for the swamp around Capitol Hill, whose political career is an extended advertisement for Beltway malfeasance, and whose only real asset — a kind of musty aura of the Obama years — is considerably diminished by his inability to speak in complete sentences?

To make a competitive run at Biden, Sanders must convince voters that he is not just the better choice, he is the safer choice. It’s not an impossible case to make — but after last night, he only has about two weeks to make it.