Former Vice President Joe Biden won what looks to be at least a narrow delegate victory in yesterday's Super Tuesday contests, which will award a third of all delegates to the Democratic National Convention in July. While the campaign is far from over, Sen. Bernie Sanders' (I-Vt.) march to the nomination that looked so likely just a week ago is a long-gone dream for the progressive left. As he and his campaign look upon the wreckage of what could have been a casual romp en route to Milwaukee, they absolutely must correct course and start the difficult process of appealing to mainstream Democrats if they want to have any hope of winning.

Let's start with the toplines: It was a bloodbath for Sanders and a bonanza for Biden. States where Sanders had the inside track just days ago, particularly Maine, Minnesota, Texas, and Massachusetts, went for Biden, who also won Virginia, North Carolina, Tennessee, Arkansas, Oklahoma, and Alabama. His margin in Virginia alone provided him with enough ballast to survive Sanders' numbers out West. Sanders got obliterated so badly in Alabama that he likely will get close to zero delegates, just a worst case scenario performance. Overall, Biden won 10 of the 14 states that voted yesterday, and while we of course do not know what the precise delegate totals will be, he has opened up a lead on Sanders that won't be easy to overcome.

And Sanders was boxed in, scoring victories only in Vermont, Colorado, Utah, and California. The Golden State win was important, because it kept him within hailing distance of Biden, but it wasn't nearly as huge as it looked like it might have been recently. If there's any silver lining for Sanders, it's that former New York City Mayor Michael Bloomberg and Massachusetts Sen. Elizabeth Warren reached viability in multiple states, holding Biden's margins down a bit and making it dramatically more likely that no one will reach a pledged delegate majority before the convention. But as the dust settles this morning, Biden has the inside track on at least a strong delegate plurality, which would make a Sanders nomination virtually unthinkable.

The tectonic shift in this race that took place over the last 7 days is unprecedented. On the night of the last Democratic debate before South Carolina voted, Sanders had a comfortable national lead as well as clear advantages in delegate sinks California and Texas. But Biden delivered a forceful performance in that debate, blew out Sanders in South Carolina, and then staged the impressive feat of convincing rivals Pete Buttigieg and Minnesota Sen. Amy Klobuchar to drop out and endorse him in the two days before Super Tuesday. While neither had much of a chance to win, collectively they controlled about 10 percent of the national electorate. That's not nothing, and it looks to have contributed to a massive movement toward Biden among late-breaking voters in the Super Tuesday electorate.

What went wrong for Bernie? Let's start with his self-destructive 60 Minutes interview on February 24th. If there's one thing that terrifies Democratic elites more than anything itself, it's Bernie's long history of sympathizing with left-wing authoritarians in places like Cuba and Nicaragua. So when he went on national television and praised Fidel Castro's literacy program from the 1960s, you could literally hear the faces of party strategists smacking into desks all across the country. There's an easy way for Sanders to handle this kind of question: "I was wrong to say anything positive about Fidel Castro, who was a brutal tyrant. But American foreign policy in these countries was still catastrophic and we should never side with dictators no matter what side of the political spectrum they happen to fall on."

Easy peasy lemon squeezy right?

Not for this guy. He can't do it. He can't walk back a mistake. And it's terrifying.

I hope this is obvious by now but there is zero conceivable political benefit to soft-pedaling your criticism of Fidel. Pro-Castro voters in America are like less than 1 percent of the electorate. As Andrew Yang might say: MATH. Someone in a position of authority in the campaign needs to pull Sanders aside and just give him a script about the 1970s and 1980s and tell him never to deviate from it. Memorize it, carve it in block letters on his arm, and read it out robotically whenever anyone asks about Cuba or the Sandinistas. Wash, rinse, shout, repeat.

Sanders also has a real and growing problem building out his coalition. While Biden was rolling up the support of the other Democratic contenders, what was Sanders doing? Did anyone reach out to Warren to see if she might drop out and endorse him? Think of it this way: At one point there were more than 20 Democrats running for president. Most of them have hit the eject button and parachuted back to safety, and the only two who endorsed Sanders were the eccentric lifestyle guru Marianne Williamson and New York City Mayor Bill DeBlasio, who was so unpopular that his candidacy was rejected immediately by the electorate like he was the wrong blood type for a transfusion.

Was Bernie ever going to be an easy sell to most of these people? No. But someone like Sen. Cory Booker (D-N.J.), who sports one of the most progressive voting records of anyone in the U.S. Senate, was probably gettable. So was Sen. Kamala Harris (D-Calif.), whose Senate record is eerily similar to Bernie's. The fact that they both sat quietly on their hands while the only progressive remaining in the race with a plausible path to victory was surging in the polls should tell you something about the Sanders campaign's outreach operation. If they don't have someone on board who can do this kind of thing, they need to get on it. Yesterday.

Bernie's troubles securing the backing of other Democrats are too broad to blame on any one particular factor. I noted in September that some personnel calls, including the decision to place strategic communications in the hands of Twitter personality David Sirota, seemed almost designed to shrink the Sanders coalition on purpose. Sure, people like Booker know who this is. You can bet that someone who works for Jim Clyburn does. Journalists who set campaign narratives do. But do normal people care about or even know who he is? No, of course not. It's a zero upside play with massive downside, in the same way that trotting Bull Durham star and 2016 Jill Stein voter Susan Sarandon out at campaign events is just mind-bogglingly self-destructive.

Everyone in the Sanders orbit was perfectly justified by pushing back hard on the insane McGovern hysteria that has gripped party elites since Iowa. To reiterate: The electability case for Sanders is almost indistinguishable from the one for Biden. But Sanders would have been well advised to do something, anything, to placate nervous Democrats, particularly older black voters who aren't inclined to gamble another four years of Trump on a Sanders nomination. There's still time, but it's running out.

This race is far from over. With Warren almost certainly on the way out, and with Bloomberg reassessing his chances, it could be a two-person scrum as early as the end of this week. Biden probably has no better than a high double-digit delegate lead on Sanders with 60 percent of delegates to come, and a contested convention is a significant possibility. In short: Almost anything is still possible.

If Sanders and his team are serious about winning this nomination, they need to scramble for support — from Warren, from any Democrat with clout, and from voters who like the Sanders platform but have reservations about his chances in the general election. If they are unable or unwilling to do that, they should resign themselves to gritting through Biden's acceptance speech in Milwaukee.

For Joe Biden, his reputation as a Democratic primary loser is gone, having staged maybe the greatest last minute comeback in primary history. A prize that he has sought now four times since 1984 is finally within his reach, and his gambit to unify Democrats around his candidacy looks prescient. But he too needs to reach out, if not to Sanders stalwarts, then to Warren supporters who might otherwise gravitate to Sanders. If he doesn't expand his coalition to include more ramparts of the left, he might also find himself with an impossible task at the convention, or worse, in charge of a party so disunited that it can't win in the fall.

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