Welcome to FiveThirtyEight’s weekly politics chat. The transcript below has been lightly edited.

sarahf (Sarah Frostenson, politics editor): Six more states vote (and Democrats Abroad wraps up its primary) today, with 365 delegates on the table. Former Vice President Joe Biden is currently projected to win all of today’s primaries, but these races are hardly all in the bag for Biden. Sanders is the underdog, but there could always be a polling surprise or two — remember the 2016 Democratic primary in Michigan.

So what are the stakes for tomorrow? And is this one of Sanders’s last opportunities to mount a comeback?

nrakich (Nathaniel Rakich, elections analyst): Yeah, it’s a pretty important day for Sanders. Several Western and Midwestern states vote today — the kind that are a good fit for Sanders — so it’s one of his last big opportunities to turn things around.

And it’s important he makes some inroads now, since next week Florida, Illinois, Ohio and Arizona are up — four big states that should be good for Biden if the state of the race stays the same.

geoffrey.skelley (Geoffrey Skelley, elections analyst): Sanders has to have a better-than-expected performance today because the rest of March isn’t great for him. Not only is March 17 bad, as Nathaniel pointed out, but then Georgia — a state Biden is expected to win handily — is the only state voting on March 24.

sarahf: Yeah, of the states up today, Michigan is just so crucial for Sanders, as it’s the biggest delegate haul on the calendar, but things don’t look good for him. He now has a 2 percent chance of winning, according to our forecast.

nrakich: Oh man, shades of 2016! Things were eerily similar before Michigan then too.

geoffrey.skelley: Polls were off by a historically large margin in the 2016 Michigan Democratic primary, but this time pollsters can use the 2016 primary to model the 2020 electorate, so hopefully that means the polls are more accurate. After all, part of the problem in 2016 was pollsters didn’t have a good recent primary to use, which contributed to the screw-up.

sarahf: That’s a fair point, Nathaniel, but watching Sanders’s odds drop precipitously over the last few days in Michigan as we got more and more polls makes me think 2016 might be the exception. Of course, as Geoffrey noted, there was a systemic polling failure in 2016, but given how much of the map Biden won on Super Tuesday — areas like Massachusetts, Maine and Minnesota — makes me think his odds aren’t being undervalued this year.

nrakich: Yeah, according to our friends at The New York Times’s The Upshot, a lot of the factors that allowed that Sanders upset in 2016 aren’t present this time around either. Specifically, Sanders hasn’t been as strong in working-class Northern strongholds this year as he was in 2016. Think about how Biden managed to beat Sanders in Maine and Minnesota. Sanders’s hope is that even though Detroit will vote for Biden, the rest of the state (which is much whiter) will vote for him. But that hope might be misplaced, as that hasn’t been the case in other parts of the country so far.

ameliatd (Amelia Thomson-DeVeaux, senior writer): But say Sanders does manage to win Michigan — wouldn’t that be an even bigger deal this year, since he’s once again an underdog but was a national front-runner just a few weeks ago?

nrakich: Yeah, Amelia, I might go so far as to say that Sanders has to win Michigan in order to prove he can strike deep enough in Biden territory to still win the nomination.

ameliatd: It does seem, anecdotally, like he’s struggling to connect with some voters of color — and in particular, black voters, since there aren’t that many Latinos in Michigan. I was at a Sanders rally at the University of Michigan Sunday night and there wasn’t a lot of racial diversity. Sanders did just get a big endorsement from Rev. Jesse Jackson, so maybe that makes a difference? But it was striking to hear that endorsement touted by Sanders and his surrogates (including Rep. Alexandria Ocasio-Cortez) in front of a mostly white crowd.

geoffrey.skelley: I’m skeptical Jackson’s endorsement is going to move a lot of voters. Yes, Jackson won Michigan when he ran for president in 1988 — which might carry some additional weight — but it was an entirely different primary setup. (It was also 32 years ago!)

sarahf: Yeah, Nathaniel pointed out a real pain point for Sanders: A lot of the factors that helped him in 2016 aren’t holding up in 2020. For instance, exit polls showed that Biden really ate into Sanders’s advantage among white voters on Super Tuesday, especially among those who decided who to support in the last few days. Biden won the majority of them (51 percent), a 28-point increase from his performance among those who had decided earlier.

White voters had the biggest last-minute swing Vote share by candidate among voters who decided in the last few days (“late” voters) and prior to the last few days (“early” voters) by race, according to exit polls in 11 Super Tuesday states Biden Sanders Group Early Late Diff. Early Late Diff. Black 60% 55% -5 17% 22% +5 White 23 51 +28 36 17 -19 Hispanic 21 37 +16 48 22 -26 All 28 49 +21 35 18 -17 Colorado is not included as its exit poll was conducted prior to Election Day to account for its mostly mail-in balloting system and it included candidates who withdrew just ahead of Super Tuesday. We don’t have exit poll data from Arkansas, Utah or American Samoa. Source: ABC NEWS/edison research

ameliatd: I’m also really curious where Sen. Elizabeth Warren’s supporters will go. As FiveThirtyEight contributor Meredith Conroy and I wrote on Monday, there’s no guarantee that they’ll line up behind Sanders — particularly white college-educated women, who made up the core of Warren’s base.

geoffrey.skelley: And because Michigan has an open primary, I’m also curious to see whether Sanders’s numbers fall in places like Ann Arbor and Kalamazoo, where there were a fair number of John Kasich voters in the 2016 GOP primary, some of whom might vote in today’s Democratic contest.

nrakich: According to exit polls, Democratic electorates in open primary states like New Hampshire and Virginia have been less liberal this year than they were in 2016 — probably because the Republican primary isn’t competitive. This has meant some Democratic-curious Republicans or Republican-leaning independents are participating in the Democratic primaries. (To be clear, this doesn’t mean die-hard Republicans are voting in the Democratic primaries in order to sow chaos.)

sarahf: So, say, our forecast is spot on and Biden wins all of tomorrow’s contests. If that happens, is Sanders’s campaign on life support? Might tomorrow night be even more important than Super Tuesday?

nrakich: If that comes to pass, when the history books (or Wikipedia articles) about this campaign are written, I still think Super Tuesday will be seen as the turning point. Super Tuesday is what put Sanders in this hole, after all.

But yes, I would agree that the campaign would be on life support if that happened, with Biden’s expected routs on March 17 (assuming they happen) serving as the death blow.

geoffrey.skelley: In the sense that Sanders’s campaign could essentially be over after today, today is more important. But as Nathaniel said, Sanders is only in this spot because Biden performed so well on Super Tuesday — it was almost the ideal outcome for him. In an alternate universe where Sanders wins Maine, Massachusetts and Minnesota, and maybe ekes things out or basically ties in Texas, the race is much closer going forward.

So yeah, Super Tuesday is still the key moment.

nrakich: Absolutely. Sanders would be the delegate leader at this point if that were true and could absorb a big Biden win.

Although is this where we point out that California is still not done counting?

geoffrey.skelley: Charles Stewart at MIT has been following the day-by-day count in California, and Sanders actually had his best day post-Election Day on March 8. He still leads by 7 points, but yeah, lots of votes left to count.

ameliatd: It does seem like Super Tuesday has led Sanders to this do-or-die moment — Michigan wouldn’t be so high-stakes if he hadn’t lost states like Minnesota. And Sanders is plainly aware of that. He has spent a lot of time in Michigan over the past few days.

I guess — thinking about more X-factors — could fears about coronavirus dampen voter turnout, particularly among older people? That could maybe help Sanders, if his younger base is more willing to brave crowded spaces and shared touchscreens.

nrakich: I’d be more worried about the effect on poll workers, to be honest.

Many of them are older and might want to stay home instead of interacting with hundreds of people. That could cause polling places to be understaffed, which could lead to longer lines.

sarahf: Oof. Coronavirus was definitely something many voters said they were concerned about on Super Tuesday, but without leaning too much into a big public health scare, I’m struggling to think of more X-factors for today. Biden’s polling bump post-South Carolina and Amy Klobuchar and Pete Buttigieg dropping out and endorsing him were just such big game-changers for Super Tuesday, it has felt a little like tomorrow is a foregone conclusion.

But OK, we didn’t see a lot of Biden’s potential strength last Tuesday until the last minute, so in that vein, two unexpected surprises for today could be: (i) The polls have overestimated Biden’s strength, or (ii) Warren dropping out boosts Sanders’s support in some of these states.

geoffrey.skelley: Biden has led nearly every state and national survey conducted since Super Tuesday. Though Emerson College did find Sanders down only 4 points in Missouri, so that’s a decent poll for him, all things considered.

ameliatd: It’s too bad for Sanders that the debate isn’t until next week, as I think he’s generally been a stronger debater than Biden. His performance could help shift momentum.

sarahf: That was one X-factor I was thinking about.

But in some ways, it feels like the debate might be a bit too late for Sanders if it’s another Biden blowout today.

ameliatd: Yeah, I agree, Sarah. I don’t think a good debate performance next Sunday can save Sanders if he bombs today.

nrakich: Mmm, I dunno, I think the debate is Sanders’s one glimmer of hope if he doesn’t score the wins he needs today.

Less so because of anything Sanders might do, but more so if Biden does something truly bone-headed.

ameliatd: Right, I think Sanders would just be relying on a bad performance from Biden. But it would have to be really, really bad, I think.

sarahf: How does the debate help Sanders moving forward, though, if some of his best states are today and he still underperforms?

nrakich: It could still affect votes for the big March 17 primaries.

I think ultimately today’s primaries are less important for what they themselves represent and more important for how they affect bigger primaries down the road (i.e., March 17). So Sanders could mayyyybe get away with a bad election night on March 10 if the March 15 debate is a game-changer.

geoffrey.skelley: I’m going to agree with the idea that Sanders could have used a debate this week instead. He needed something to change the conversation, and that hasn’t happened.

ameliatd: And the important thing is that Biden’s performance is not really in Sanders’s control. If you go into the debate just hoping that your opponent steps in it — that’s not a good place to be.

nrakich: Totally agree with that, Amelia.

ameliatd: I also don’t think it helps Sanders that many former Democratic candidates are coalescing around Biden. He appeared at a rally in Detroit Monday night with Sens. Cory Booker and Kamala Harris. Meanwhile, Sanders doesn’t have an endorsement from Warren, this cycle’s most prominent other progressive candidate.

geoffrey.skelley: Right, among the former 2020 candidates Sanders has earned the backing of just New York Mayor Bill de Blasio and Marianne Williamson, which is in stark contrast to Biden, who has earned the endorsements of almost half of the other candidates who ran, including Booker, Buttigieg, Harris, Klobuchar, John Delaney, Deval Patrick, Michael Bloomberg, Beto O’Rourke and Tim Ryan.

ameliatd: A couple people at the Sanders rally on Sunday night said they were hoping Biden will pick Klobuchar or Harris as his running mate. Of course, I don’t think Biden is going to announce his VP pick today. But their endorsements could be reassuring to people who think Democrats need a woman or a person of color on the ticket in November.

geoffrey.skelley: Interesting, were those Sanders voters or just curious undecideds?

ameliatd: Curious undecideds! One of them told me he was at the rally because he wanted to “feel the Bern,” but wasn’t there yet.

sarahf: It does feel as if the race has entered that phase where we know the ending: that is, Biden will win this thing outright. And I guess, while the primary definitely won’t be over tomorrow if Biden dominates again (I can’t see Sanders dropping out before the debate on Sunday), the overall trajectory seems pretty baked in at this point, barring some big Sanders upsets.

Is that fair? It just seems as if there are genuinely fewer possible surprises this time around, aside from a systemic polling error or a scary coronavirus-related outbreak (which … let’s not game that out 😬).

nrakich: Yeah, I think that’s definitely fair, Sarah. These things fall along a spectrum, but it’s just varying degrees of bad news for Sanders: Right now he is pretty screwed. If he does poorly on March 10, he will be on life support. If he does poorly on March 17, he will be totally done for.

geoffrey.skelley: On the most recent installment of the FiveThirtyEight Politics podcast’s “Model Talk,” editor-in-chief Nate Silver described the events of Super Tuesday as basically Biden’s 90th to 95th percentile outcome. That is, it was about as good as he could have hoped for. Because of that, Biden has been set up very nicely for the remainder of March in a bunch of states that are now better for him than Sanders. In other words, it’ll be very difficult for Sanders to overtake Biden. But of course, the proof is the pudding — that is, the actual results.

ameliatd: It does feel like Sanders is running out of opportunities to turn things around. A bunch of things lined up last week in Biden’s favor — so maybe that could still happen for Sanders? But this is his dramatic comeback moment, if he’s going to have one.