This argument by Philip Klein is defensible but counterintuitive. One thing we learned last night is that “the lanes are real,” as Jonathan Last put it, with Biden piling up unexpected numbers of votes after Buttigieg and Klobuchar quit the race. For the past year we’ve been analyzing the race as a contest between the “progressive lane” and the “moderate lane,” knowing all the while that that’s a gross simplification of how actual people vote. For instance, some Bernie fans had Biden as their number two, and vice versa, because they preferred a nominee with working-class appeal more so than someone who matches them closely on ideology. Some Klobuchar fans had Warren as their number two, and vice versa, because they thought it was important to have a woman nominee this time. People don’t fall in love politically for neat little reasons like “X is more supportive of raising taxes on the rich than Y.” It’s complicated. The “lane” interpretation of the race is … not complicated.

Yet there was Joe last night, coming out of nowhere to win Klobuchar’s home state of Minnesota and the southern states where Bloomberg had competed aggressively. As the centrist “lane” collapsed behind him, his numbers skyrocketed. There are lanes!

But I wonder if maybe the lanes all along weren’t “progressives” and “moderates” so much as “socialists” and “not socialists.” There’s only ever been one candidate in the socialist lane. And there are only two remaining in the “not socialist” lane as I write this at 4 p.m. ET. If Warren, one of those two (nominal) non-socialists, hangs in there, are we sure she’d take more votes from Bernie than she would from Joe? Klein makes another point: If Biden, not Bernie, is now the frontrunner in the race, isn’t it paramount to keep his delegate totals as low as possible so that he doesn’t clinch a majority before the convention? Unquestionably, Warren will be hoarding some votes from Biden if she remains in the race (although maybe not as many as she hoards from Bernie). Those votes may end up being the difference between an outright Joe win and a contested convention.

Following his huge Super Tuesday, Biden is in strong position to win the most delegates in the Democratic primaries, if not an outright majority. And if Biden falls short of a majority, the good news is that as things stand now, most of the remaining delegates (i.e. those not won by him or Sanders) have gone to people who are now endorsing him. With results still pouring in from California, the New York Times Upshot model is projecting that Biden will come out of the big day with 45% of the delegates. But if you add the projected totals of recent Biden endorsers Bloomberg (104 delegates), Pete Buttigieg (26 delegates) and Amy Klobuchar (7 delegates), then he actually ends up with a majority. Put another way, if Biden is close to a majority but not quite there going into the convention, other candidates with a total of 137 pledge delegates would be asking their delegates to vote Biden on the first ballot and prevent a contested convention.

If Warren drops out now, according to the same model, she would only have 97 delegates — so she wouldn’t be in as much of a position to help Sanders. However, if she remains in the race, she could still keep amassing delegates. Were delegates to be split three ways instead of two in a number of contests, it will become harder for Biden to achieve a majority. At some point, maybe as soon as next week, she could pass the Bloomberg-Buttigieg-Klobuchar total, giving her more influence then them if no candidate receives a majority.

She could also help Bernie by teaming up with him against Biden at the next debate, Klein notes. Here’s an interesting number:

-If- Warren Does Drop Out, Here's The Most Recent Second Choice Support For Warren Voters From Morning Consult:

Sanders: 40%
Biden: 16%
*Buttigieg: 16%
*Klobuchar: 12%

*Dropped Out

Morning Consult / February 27, 2020 / Online

— Polling USA (@USA_Polling) March 4, 2020

*If* you assume that all of the Warren voters with Buttigieg or Klobuchar as their second choice would now go to Biden (which they wouldn’t, although most probably would), then Warren’s presence in the race is withholding 44 percent of her voters from Biden versus just 40 percent from Bernie. It’s a net gain for Sanders — which makes sense when you think about it. Warren’s remaining left-wing supporters have had every reason to this point to abandon ship and join the Bernie brigades: He’s led her in the polls for three months, he won three early states while she was an also-ran, he’s raised huge sums of money while she struggled until very recently. Some progressives in Warren’s corner are obviously skittish about Sanders to have resisted the pressures to switch to him for so long. It’s no sure thing that there’ll be mass defections to his campaign if she quits.

Even if she drops out, the Biden/Buttigieg/Klobuchar preferences among her voters will ensure that Biden gets a healthy cut of her support, largely offsetting Bernie’s windfall. Remember, Warren has been selling herself as a goldilocks candidate, a less socialist Bernie to centrists and a more socialist Biden to progressives. She has some centrist support. That support’s probably going to Joe once she’s out. Which means her exit could have a negligible effect on the race, especially if Joementum continues to burst in next week’s primaries.

One question about Klein’s scenario, though. Is there any outcome going forward, realistically, in which Bernie’s and Warren’s combined delegate total exceeds that of Biden plus everybody else? Klein is imagining Biden finishing with 45 percent of all delegates, say, Bernie finishing with 43 percent, and Warren finishing with eight percent. Joe would say he deserves to be the nominee by dint of his plurality but Sanders and Warren would counter that Bernie deserves to be nominee by dint of the combined 51 percent of delegates who voted for an ardent progressive. Such is the theory. How likely is it, though, that Warren will retain enough support to take meaningful bites out of Biden’s (and Sanders’s) haul in state after state, month after month, long after Democratic voters have concluded that this is a two-man race? Nate Silver wonders:

That is, the Warren supporters who really like Bernie (or Biden) will probably go to to Bernie (or Biden) *whether or not she drops out*. Many of them likely already have, in fact.

— Nate Silver (@NateSilver538) March 4, 2020

She doesn’t need to formally withdraw for her voters to abandon her. Meanwhile, it may be that Biden is now enough of a juggernaut that he’ll never relinquish the national delegate lead even if that lead remains modest:

A three-point deficit is not a daunting handicap, certainly not when Mr. Biden was polling 20 points lower just a few days ago. But the Super Tuesday results do not augur well for Mr. Sanders’s odds of pulling it off. He remained so competitive on Super Tuesday in part because of the large number of early and absentee voters who cast ballots before it became apparent that Mr. Biden was the viable moderate candidate.

The rest of the country may not be so favorable to Mr. Sanders, either. With Texas and California off the board, most of the remaining populous states lie in the East, where Mr. Sanders tended to lose, often badly. They also tend to have a below-average Latino share of the vote.

The states where Latino voters do represent roughly an average share of the electorate do not seem likely to be as favorable to Mr. Sanders as California or Texas.

Where does the “Bernie comeback” happen, exactly? Even if Warren hung in there and helped hold Biden below a majority of delegates before the convention, try to imagine a scenario in which Joe arrives in Milwaukee with a plurality and the Biden-friendly establishment at the convention decides to nominate … a second-place socialist with a heart condition and weak African-American support over their favored candidate. It’ll never happen. A Joe plurality will be enough to ensure his nomination. So Warren might as well quit, endorse Bernie, and try to repair relations with progressives who momentarily hate her for having drawn votes away from Sanders last night.

One more point. I disagree with this:

But I think Jilani is right that if Sandersistas want to blame Warren for something, it isn’t that she stayed in the race too long; it’s that she drove a progressive arms race that seems to have hurt both of their chances in the end.

— Ross Douthat (@DouthatNYT) March 4, 2020

I’ll never believe that Bernie would have tacked to the center even if he had had all the political space he could have asked for to do it. His entire identity as a politician is that he won’t compromise on his beliefs, even when it’s in his political interest to do so. WYSIWYG. Douthat’s point is truer in reverse: If Sanders hadn’t run this year, Warren would have had more room to finesse her support for Medicare for All. As it was, she had to stick to it to appease progressive voters for fear that they’d come to view her as a sellout if she tried to move to the center for electability reasons. In the end they viewed her as a sellout anyway and meanwhile her support for M4A poisoned her appeal to centrists. Bernie killed the Warren campaign by running in 2020 much more so than Warren killed Bernie.

Here he is this afternoon, trying not to pressure her to quit and endorse him.

Sen. Sanders says he spoke with Sen. Warren on Wednesday, saying Warren told him that “she is assessing her campaign, she has not made any decisions as of this point,” adding that it is important "to respect the time and the space that she needs to make her decision.” pic.twitter.com/1jNo2fPedd

— MSNBC (@MSNBC) March 4, 2020