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

sarahf (Sarah Frostenson, politics editor): On Monday, a new national Monmouth poll found that Joe Biden’s status as the 2020 Democratic front-runner may be in jeopardy. The former vice president is no longer the sole candidate at the top of the pack: Rather, the pollster found him, at 19 percent support, in a three-way tie for first with Sens. Elizabeth Warren and Bernie Sanders, both at 20 percent.

Of course, this is just one poll and Biden still has the highest polling average at 28 percent, according to Real Clear Politics. But it’s also possible that the dynamics of this race, which up until this point have been pretty stable, are finally shifting, with Biden on the decline and Warren and Sanders on the upswing.

In fact, could Warren be the new front-runner? She and Sanders are neck and neck in their RCP polling averages — and according to The Economist’s polling average, she’s actually now in second. What’s more, since Warren entered the race in January, she has steadily moved from polling in the single digits and fifth or sixth place nationally to the double digits and second and third place. So what evidence do we have to support the idea that Warren in the lead (or close to it)? Or if you don’t think Warren is the front-runner, who do you think is?

nrakich (Nathaniel Rakich, elections analyst): I think Biden is still pretty clearly the front-runner. The vast majority of polls still give him a healthy lead.

natesilver (Nate Silver, editor in chief): She’s not in the lead nationally. You could maaaaaayayayayayayaybe convince me that she’s the most likely to win the nomination, though.

nrakich: That said, if your question is, “Is Elizabeth Warren one of the two most likely Democratic nominees?” I would answer yes for sure.

natesilver: C’mon, that’s a cop-out, Nathaniel!

sarahf: srsly

ameliatd (Amelia Thomson-DeVeaux, senior writer): Could we say that she is a front-runner? I think that’s becoming more and more plausible, and also maybe less of a cop-out.

Warren’s slow but steady growth in support is worth taking very seriously. Maybe she’s not the front-runner but she’s an increasingly serious threat to Biden.

And given the fact that we’ve heard over and over again that voters are concerned about nominating a woman, Warren’s increasing support is that much more impressive.

natesilver: I’d say she’s one of the 20 most likely winners.

nrakich: Fine, I’ll rephrase — I think Warren is the second-most likely nominee.

I still think Biden is the most likely.

Flag, planted.

natesilver: I feel like someone has to play devil’s advocate here.

Maybe I’ll do that? Even though I’m not totally sure I buy it?

sarahf: So, I realize Monmouth is just one poll. And of course, Monmouth wasn’t even the only poll to drop Monday. Morning Consult also released its weekly tracking poll, which found Biden in the lead with 33 percent, Sanders in second with 20 percent and Warren in third at 15 percent. So Nathaniel is right that Biden is still the front-runner — I’m not really disputing that.

What I am curious to know is whether the tides are changing and there is evidence that Warren could usurp the lead.

natesilver: Oh, my devil’s advocate case wouldn’t even reference the Monmouth poll at all. Because I’m a good devil’s advocate, not a facetious one.

sarahf: Ha, so what’s the devil’s advocate argument here?

natesilver: The devil’s advocate case is just that she’s been moving up steadily, she’s the most likely candidate to win Iowa, she has the best favorables in the field, she might have the best campaign organization and Biden — although probably a little UNDER-rated on balance — has a lot of vulnerabilities.

sarahf: Huh, I guess I don’t think of that as a devil’s advocate argument. Sounds like an explanation for why Warren is now in second or third, depending on what polling average you look at, and a reason why she might continue to climb upward in the polls.

nrakich: Here’s how I think the argument goes for why Warren isn’t in first place today but might wind up on top: We don’t hold a national primary day. If we did, Biden would be on much safer ground with his polling lead. But as it stands, Warren has a clear path to winning the first three primary states:

As Nate alluded to, Warren is a good fit for Iowa. She has led some polls there, and she’s not that far behind Biden in others. Relatedly, Biden is relatively weak in Iowa, as Nate wrote recently — he has just the fifth-best favorable rating of any candidate there. (And guess who’s in first?)

Warren is better-liked than Biden in Iowa Average favorability of Democratic primary candidates in Iowa polls Favorable Unfavorable Candidate Strongly Somewhat Total Somewhat Strongly Total Warren 46% 34% 80% 6% 4% 11% Harris 40 33 73 6 4 10 Buttigieg 40 32 72 5 3 7 Sanders 32 37 68 15 9 24 Biden 31 36 67 16 8 24 Booker 22 42 63 10 3 13 Klobuchar 15 34 49 11 3 15 Castro 14 34 48 7 3 10 O’Rourke 12 40 52 13 6 19 Gillibrand 8 33 40 14 6 20 Gabbard 7 25 32 13 7 20 Delaney 5 20 25 13 7 20 Yang 5 18 23 14 6 19 Bullock 5 16 21 8 3 11 de Blasio 3 19 22 24 11 35 Bennet 3 16 19 9 3 12 Williamson 2 9 10 17 14 31 Ryan 2 14 16 13 5 18 Average of Iowa polls from Selzer & Co., Change Research and David Binder Research. Totals may not add up exactly due to rounding. “Strongly” includes respondents who answered “very strongly” Source: Polls

Plus, as a candidate from next-door Massachusetts, Warren already has home-field advantage in New Hampshire. And if she does win Iowa, that will give her a boost heading into the Granite State. If she wins Iowa and New Hampshire, she will definitely have a boost going into the next state, Nevada. Nevada is also a heavily unionized state, which seems like a good fit for her. Plus, former Senate Majority Leader Harry Reid is reportedly partial to Warren, and he might be willing to deploy his powerful turnout machine on her behalf. (Although Warren already has a pretty good campaign apparatus in Nevada on her own!)

So despite Biden’s lead in national polls, the actual state-by-state results might lead to a Warren nomination more often.

natesilver: Meh, I think the momentum shit is overrated.

The momentum shit from winning primaries, that is.

Like, it’s not nothing. It’s something! But, if you look at the Obama-Clinton contest in 2008, or Clinton-Sanders in 2016, the vast majority of who does better in which state is determined by demographics, not timing.

nrakich: Right, but I don’t think my argument relies on Warren winning, say, Iowa in order to keep her afloat in subsequent states. Warren has some natural advantages in New Hampshire and Nevada, too. Any momentum from winning previous states just makes her case for winning them even stronger.

natesilver: But then Biden wins South Carolina by six million points and who has the momentum on Super Tuesday?

ameliatd: On the demographics issue, one big question I have about Warren is how she will continue to broaden her support. She’s significantly more popular among white voters than black or Hispanic voters, and that could pose a serious problem for her.

nrakich: Combining Nate’s and Amelia’s points, certainly her weakness with black voters — who constitute almost a quarter of the Democratic primary electorate — is a problem for Warren.

natesilver: WhY aRe YoU gUyS eRaSiNg BeRnIe?

sarahf: Ha, I was just going to get to that.

Ostensibly, Warren and Sanders are roughly in the same place in the polls — Sanders has a poll average of 17.7 percent and Warren 16.0 percent, according to RCP. So are there actually two new front-runners?

ameliatd: How many front-runners is too many front-runners??

natesilver: Not in my view, no. I think Warren and Biden are No. 1 and 2 for likelihood of winning the nomination in some order, and I think Sanders is No. 3.

Why? First of all, Warren’s polls are a bit better than Sanders. She has roughly equal support nationally despite being less well known, and she has slightly better net favorables. She’s doing better in Iowa. And she has more upward momentum, although that can be overrated.

Second, if you put any weight on the sort of “party decides” view of the race, the party establishment seems to view her as being quite a bit more acceptable than Bernie, although she doesn’t have a ton of endorsements yet.

nrakich: Yeah, Sanders does not appear to be interested in expanding his coalition; he’s pretty much been stuck polling in the same 15-to-18 percent range since Biden entered the race, whereas Warren has been steadily winning people over. According to The Economist, only 38 percent of Democrats are considering voting for Sanders, whereas 49 percent are considering voting for Warren … which is even (slightly) more than the 48 percent who are considering voting for Biden!

ameliatd: Warren does seem to be doing quite a bit of work to position herself as a progressive candidate who’s also not a threat to the Democratic establishment — which is not Bernie’s typical M.O.

natesilver: That Economist poll has generally had good numbers for Warren, though. So I’d be a little careful there.

But polls do show that more informed voters are generally more into Warren than Sanders. So that’s another bad sign for Bernie (and Biden). As voters tune in, they seem to gravitate toward Warren more.

sarahf: I also thought the second quarter’s fundraising numbers were particularly telling when it came to support for Warren and Sanders. Warren tripled her numbers from the first quarter and raised the third-most from individual contributors, after Pete Buttiegieg and Biden (and before Sanders). And even though a greater percentage of Sanders’s donations currently come from small donors (or those giving $200 or less) than Warren, a Los Angeles Times analysis found that more than 80 percent of the donors who funded Sanders’s 2016 bid have not given to him this cycle, so this is, to me, evidence of a larger enthusiasm problem with Sanders.

And that’s important, because rightly or wrongly, Warren and Sanders are going to have to work to distinguish themselves from each other.

nrakich: I think they’re already distinguishing themselves, Sarah. Even though they’re not attacking each other, Warren has made clear efforts, as Amelia said, to show that she can play nice with the establishment. Sanders has continued to rail against economic and political institutions.

sarahf: And I guess at this point, Warren and Sanders’s bases are pretty different from each other, right?

natesilver: Well, part of the reason their bases are different now is because Warren has stolen most of the college-educated left from Bernie.

So what’s over in Sanders’s coalition is a bit eclectic — some real dyed-in-the-wool anti-establishment types, but also some non-college educated voters who aren’t necessarily that far to the left but like his populism or just like his message and personality.

nrakich: There is a big gender gap between Warren and Sanders, though. According to a Quinnipiac poll from early August, Sanders is second among men with 19 percent support, and Warren is third with 16 percent. But among women, Warren is second with 24 percent, and Sanders is third with 10 percent. (Biden is in first with both groups.)

sarahf: Are there more opportunities for Warren to continue to take voters away from Sanders? Or is she better off targeting voters from, say, Biden or Harris?

ameliatd: Isn’t Warren already siphoning some support from Harris? There seemed to be overlap between their supporters, at least earlier in the summer.

nrakich: Right. And my guess, Amelia, is that a lot of the voters who jumped on the Harris train after the first debate have since decamped to Warren.

And to Nate’s point, I suspect a lot of those 2016 Sanders voters without college degrees are now with Biden. So Sanders is kind of getting pinched from all sides.

natesilver: Yeah, I definitely think there’s evidence of a Harris-Warren overlap.

ameliatd: I also wonder how much some combination of sexism and electability concerns are holding Warren back, and how that will play out as the primary moves forward. There was some research earlier in the summer suggesting that both Warren and Harris were taking a hit among Democratic voters with more sexist views. And then there are the meta-sexism concerns from people who think a woman will have a harder time getting elected. As she continues to build support, maybe she’s chipping away at the latter? It’s obviously a hard thing to measure.

nrakich: Yeah, Amelia, maybe some voters have realized that Biden isn’t as electable as they thought, after seeing him struggle in the debates.

ameliatd: That would be my guess, Nathaniel. Although it’s interesting that Biden and Warren have yet to be on a debate stage together. If that happens next month (fingers crossed for one night!) maybe that shifts the dynamic between the two?

natesilver: It almost feels like there’s some weird shit like this going on, in terms of how voters are flowing between the candidates.

sarahf: Omg. What is that?

nrakich: Hahaha. I think that’s pretty good! My most recent piece on lanes in the Democratic primary indeed found that there is very little overlap between Sanders and Harris supporters, and not much between Warren and Biden supporters either.

ameliatd: But in terms of Warren being able to pull more supporters from Harris, a strong debate performance against Biden couldn’t hurt.

natesilver: IDK, if we’re forced to have two debates, the DNC could draw the rules up such that candidates who haven’t faced one another yet are more likely to be paired.

sarahf: I’m not so sure Warren can’t eat more into Biden’s support, though. Another thing that I thought was interesting in that Monmouth poll is that they found that among moderates who haven’t been paying as much attention, there is evidence they are swinging toward Sanders or Warren instead of toward a lesser-known candidate who might be more of an ideological fit.

And maybe this is just further proof that lanes don’t really exist, but it is interesting to me that among the more moderate candidates, there doesn’t seem to be an ordained alternative to Biden.

natesilver: Maybe it’s Buttigieg? But he’s still sort of a niche brand.

ameliatd: Is Harris’s name-recognition really that much lower than Warren or Sanders’s, though? It’s interesting, because moderates don’t seem to be flocking to her, and she’s someone who you think they’d be interested in.

natesilver: Yeah, I don’t know why there are so many WHY IS BIDEN STRUGGLING?!?!? takes when Harris is clearly the one who’s had a rough month or so in the polls.

nrakich: Amelia, 79 percent of Democrats can form an opinion of Harris, according to an average of August polls. That’s comparable to the 83 percent who can form an opinion of Warren. Biden and Sanders are noticeably higher — they have almost universal name recognition within the party.

sarahf: It’s true that Harris has had a much rougher month in the polls than Biden, but something else that stuck out to me in Nathaniel’s story was that Biden had the biggest drop of any candidate in his net favorability rating (favorable rating minus unfavorable rating) — he dropped 8 points from May to August, and 17 points from the beginning of the year. So I think, even if Harris might be down more at this particular point in time, some of the conventional wisdom might be that she has more of an opportunity to gain back what she’s lost in the polls than Biden?

ameliatd: I wonder if Harris’s flaw is that she’s not so easily categorized. People know who she is, but she’s kind of been staking out a middle ground between the moderates and the liberals. Warren, on the other hand, has a clear brand, which could be helping her right now. Maybe there’s room for Harris to recover, though?

nrakich: Frankly, I think primaries are periods of ebbs and flows. Right now, Harris and Sanders are down, while Biden and Warren are up (Biden more in the absolute sense, Warren more in the relative sense). But Harris and Sanders have shown the ability to appeal to these now-Warren-and-Biden-supporters before. So if they campaign smartly, they could certainly gain them back.

natesilver: Yeah, Amelia, that was basically the critique I had of Harris: She’s trying to split the difference and it … isn’t working, right now at least. But a campaign like Harris’s, which doesn’t have as clearly defined of a base, is inherently liable to be more volatile than someone with more of a base of their own.

ameliatd: But Warren has been steadily gaining support for months. And that seems hard to dismiss, especially with all of this movement. Unless she eventually hits some kind of ceiling, of course.

nrakich: I think it’s definitely a good sign for Warren that her increase has been slow and steady, instead of a Buttigiegian “bump.”

sarahf: OK, pulse check. No one at the beginning of this chat was willing to say Warren is the front-runner, and maybe that’s still true. But let’s wrap by talking about where you see her in the race currently, and what you’re going to be watching for going forward.

natesilver: I’m gonna be watching for whether she can gain more traction with non-college educated voters, and with black voters. And I’m gonna be watching if she gets more endorsements. We haven’t really taken the time in this chat to make the case against Warren, but those three things above would be a big part of it.

ameliatd: I will be really curious to see what happens when Warren ends up on a debate stage with Biden, and whether that helps defuse any more electability concerns.

nrakich: I see Warren as a clear No. 2. And there are a couple of good indicators for her that, if she eventually overtakes Biden, we will point to as early signs of that. But I think I will mostly look to see if coverage of Biden continues to be skeptical and if his favorability ratings continue to decline.

natesilver: Ehhhhhhhhhhhhhhh I sort of disagree with Rakich. I think Warren’s chances are more about Warren than Biden.

Biden’s at, IDK, 29 percent right now. And maybe 23 or 24 percent in Iowa or something. It shouldn’t be that hard for Warren to surpass him even if he doesn’t decline at all.

nrakich: Nate makes a good point, and I could easily see the race boiling down to Warren vs. Biden by Super Tuesday. But for Warren to become a favorite over Biden, as opposed to a co-front-runner? I think Biden has to help out with that.

ameliatd: Warren is gaining on Biden — and seems to be surpassing Sanders — but it’s probably still important to watch how she performs relative to Harris, too.

Despite having some overlap in supporters, they also haven’t gone after each other — does that start to change, if Harris sees Warren as a threat?

sarahf: Yeah, we didn’t really talk about the case against Warren — but I think Nate’s landed on one of her biggest vulnerabilities: Can she win over more voters who aren’t white? Currently, as you’ve all mentioned, the crosstabs aren’t really there, but if she can build support, I think she emerges as a true front-runner. Otherwise, I think someone like Biden (or Harris) continues to have broader appeal.

nrakich: Right, Sarah. There’s also the possibility her favorability ratings decline, too. There is ample opposition research against her, like her claims of Native American ancestry and her past as a Republican, that hasn’t come up a lot in recent months but could still hurt her.

Now that I think about it, one of the benefits to Warren’s steady rise, as opposed to a sudden surge, is that she didn’t immediately get thrust into the “discovery, scrutiny, decline” cycle. Her rise has been so gradual, it might have snuck up on people. So I guess another thing I’ll be looking for is if the media, voters and her opponents start assessing her more critically.

natesilver: We should also maybe be a little bit skeptical of candidates whose support is concentrated among college-educated white people, which happens to be the demographic that the media both caters to and belongs to.

Bernie’s support is actually notably more diverse than Warren’s, and Biden’s certainly is.

ameliatd: But I do think Warren has room to grow, especially among women, if voters are actually starting to be less concerned about electability. Granted, right now, she’s doing much better among white women than women of color right now — but that could change.