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

sarahf (Sarah Frostenson, politics editor): With the spread of the new coronavirus in the U.S., the 2020 Democratic primary is on a bit of a hiatus. Many states have postponed their primaries, and now we might not wrap things up until late June. But the expected outcome is hardly a surprise — former Vice President Joe Biden is for all intents and purposes the presumptive nominee.

Sen. Bernie Sanders is still in the race, but at this point, the question is less about what Sanders can do to mount a comeback and more about what Biden can do — if anything — to win over Sanders voters, particularly as we start to transition to the general-election phase of 2020.

So, let’s unpack this question in three parts:

First, how much does Biden need Sanders supporters? Or in other words, what does it mean for Biden’s base of support if he’s able to win over Sanders supporters? What does it mean if he can’t?

Second, how does Biden actually win over Sanders supporters?

And third, how important is party unity — or Democrats rallying behind one candidate — for what happens in 2020?

nrakich (Nathaniel Rakich, elections analyst): Well, this is so obvious that it sounds stupid to say out loud, but: Biden needs some Sanders primary voters to support him in November, since Sanders has won about 31 percent of the national popular vote so far. But he doesn’t need every single one.

Some Sanders-or-bust voters might stay home in November; that happens to some degree in every election.

But most Sanders voters don’t fit that description. According to a recent Morning Consult poll, 82 percent of Sanders supporters say they would vote for Biden in the general election, and just 7 percent said they would vote for Trump. And Quinnipiac University found that 86 percent of Sanders voters would vote for Biden, 3 percent would vote for Trump, 2 percent would vote for someone else, 4 percent wouldn’t vote, and 5 percent didn’t know who they’d vote for.

geoffrey.skelley (Geoffrey Skelley, elections analyst): Yeah, I mean, you have polls showing Biden winning ~90 percent of Democrats in general election trial heats against Trump. So he’s likely winning over most Sanders voters. But if a Trump-Biden matchup were to be a close election like 2016, any shortfall in support from Sanders voters would be magnified.

nrakich: Yeah, Biden should certainly want to win over as many Sanders supporters as possible.

Every little bit counts!

sarahf: One thing you’ve written about for the site, Perry, is the age divide we’ve seen play out in the Democratic primary with Sanders consistently winning voters under 45.

But you’ve also written that these voters generally vote Democratic in a general election, so maybe Biden doesn’t have to worry all that much about making special inroads here? That is, it will come with time?

perry (Perry Bacon Jr., senior writer): Every bit of enthusiasm and turnout from younger voters helps Biden. That said, it’s worth separating the cohort of people under 45 from the “Sanders-or-bust” people. Overall, I think the under 45 group will be fine with Biden because they hate Trump more.

geoffrey.skelley: Data from the Cooperative Congressional Election Study suggested that about three-fourths of Sanders’s voters backed Hillary Clinton in 2016. Might that number be higher in 2020? Maybe.

On the one hand, it’s possible that some of the anti-Hillary, conservative Democratic voters that Sanders won in places like Oklahoma and West Virginia are now Republicans who didn’t participate in the 2020 primary. But it’s also possible that a handful of those voters back Biden. For instance, he’s already been doing better than Sanders among white primary voters without a college degree, a group Sanders won handily in 2016.

So the tradeoff for Biden in 2020 may be that he loses youth turnout but gets more votes from suburban moderate types who are older. Given that older voters are more reliable voters, that might be an OK trade for Biden.

nrakich: Yeah, I think there are a lot more votes up for grabs among suburban Romney-Clinton voters than there are among young voters.

Biden winning suburban areas in the primary doesn’t necessarily mean he’ll win them in the general (the actual voters are different — primaries are just a fraction of the general electorate). But as a more moderate candidate who doesn’t rail against the rich, he is likely to appeal more to these more moderate, well-to-do voters than Sanders.

sarahf: That makes sense, especially based on your analysis, Nathaniel, of turnout in the primary so far, but I can’t help but wonder about your other point — voters in the primary are different than the general — so maybe some of Biden’s support among the Romney-Clinton style voters is inflated?

Or the fact that Biden has won rural areas that Clinton did poorly in in 2016 isn’t actually that good of a sign for his coalition in a general election context? So maybe young and very liberal voters will actually be very important to Biden’s coalition?

nrakich: People shouldn’t use primary election results as a portent of the general election. Biden won every county in Michigan in the primary, but he obviously won’t do that in the general. Winning white working-class Democrats isn’t the same as winning white working-class independents or Republicans. That said, I don’t think it’s a bad sign for him that turnout was up so much in highly educated suburban areas.

perry: Biden should try to win older voters and younger voters, moderate voters and liberal voters, and I don’t necessarily see those things as trade-offs. Obama was stronger than Clinton across all kinds of voting blocs in 2008.

So getting younger voters excited about his candidacy is important and useful for Biden. He will likely win the under 45 vote (historically, Democrats do), but growing that margin should be a goal of his campaign.

sarahf: OK, so what does Biden do to actually win over Sanders supporters?

nrakich: Well, the first and most obvious answer is to adopt some of Sanders’s positions. He has already started moving left (although, it should be noted, not as far left as Sanders) on issues like free college tuition — quite savvily, in my opinion, because that is one progressive policy that actually has strong support among all voters, not just Democrats.

geoffrey.skelley: Exactly. That seems like a pretty transparent play for younger voters, and possibly older millennials who like Sanders and who also have kids and are starting to think about how they’ll pay for college some day.

nrakich: Two other progressive positions that Biden could take without alienating general-election voters are coming out in favor of legalizing marijuana and implementing an Elizabeth Warren-style wealth tax.

geoffrey.skelley: Of course, the latter might alienate some donors.

nrakich: True.

I also don’t think Biden will ever fully replace Sanders in many voters’ minds — a lot of Sanders’s appeal is based on his personality and tear-down-the-system rhetoric.

geoffrey.skelley: Yeah, and Biden’s appeal has been that of a safe harbor in a storm — even more so now that we face the new coronavirus threat. He’s interested in reforming the system, not breaking it up and then rebuilding it.

perry: I honestly don’t think Biden has to do much of anything to win the votes of the overwhelming majority of Sanders voters — except to not be Trump. The question is more about, “How does he get them excited?” The danger of Biden is that he is like Clinton in 2016 — he wins the votes of the older, traditional Democrats in the primary, but he is not a candidate people are jazzed about — and that shows up in voter turnout, in donations, in the general mood of the campaign.

Biden can’t be Obama in 2008, but he should avoid being Clinton in 2016 or Kerry in 2004. I think he should aim for a running mate people are really excited to vote for.

geoffrey.skelley: Is that Sen. Kamala Harris? I don’t see it being Sen. Amy Klobuchar.

perry: Geoff, I honestly don’t know who that person is. But I think it should be an Obama-like person — exciting less in terms of policy (the party is divided on policy) but more in terms of persona and charisma.

As I was saying earlier, Biden should focus on energizing “Democrats under 45,” not “Sanders supporters.”

nrakich: The problem is that everyone has a different definition of who is “exciting.” The stereotypical leftist Sanders voter isn’t going to be jazzed about Harris, who has her own problems among the progressive flank. Maybe not even someone like Stacey Abrams, who appeals to the “woke” wing of the party but is certainly closer to Biden than Sanders on policy.

And then there is the fact that it’s debatable how much of an impact vice-presidential candidates even have.

sarahf: That makes sense, Perry, definitely from a messaging vantage point, anyway. But right, to Nathaniel’s point, it’s hard for me to imagine Sanders voters being excited by Harris as his VP pick. But maybe that’s the point — it isn’t about the diehard loyal fans as much as it is about just generally energizing younger voters.

That especially holds true given that turnout in these primaries hasn’t been historic, as many thought it would be.

It’s easy to read too much into the primary and try to apply that to the general election, but the turnout question for 2020 does give me pause, especially if Biden, like you say, is someone the Democratic Party rallies around but isn’t necessarily jazzed about.

nrakich: But how many young voters are against Biden because he’s not far left enough, and how many are against him because they just want a new generation of leadership? I genuinely don’t know.

perry: I think the second group (new generation of leadership) is both bigger and easier to satisfy (because moving left might create electoral problems).

geoffrey.skelley: Right. Pew Research found back in 2017 that while younger Democrats and those who leaned Democratic were more liberal than older Democrats, they weren’t that much more liberal.

sarahf: So how important is party unity for what happens in 2020? As has been said in this chat, in many ways the biggest factor for the Democratic nominee is that they’re not Trump. That said, is there a risk that Democrats don’t rally behind Biden? After all, that was a critique of what happened in 2016, with some arguing Sanders cost Clinton the election. Could that happen again in 2020?

perry: Party unity is super important. But I think Trump will create party unity. Sanders and Warren will eventually be strongly behind Biden. And the biggest difference between 2016 and 2020 is not between Clinton and Biden (they are very similar candidates) but between Trump 2016 (theoretical) and Trump 2020 (a reality Democrats hate). Because of Trump, some of the problems Clinton faced in getting the base behind her won’t be as much of an issue for Biden.

nrakich: Yeah, I think we’ve been getting at this question indirectly. Party unity will be important, sure, but according to the polls cited above, Democrats largely already have it. And some of those Sanders voters who may have cost Clinton the 2016 general election may have just been anti-Clinton voters in the primary as well. It doesn’t seem like there is a rash of anti-Biden protest voting this year.

geoffrey.skelley: It helps to not have been a target of attacks for a quarter century before becoming your party’s nominee.

Also, while we do have some exit-poll data suggesting some Sanders voters might not want to vote for Biden, it’s important to remember that some might answer that question differently once they are no longer in the thick of the primary. I’m reminded of “Party Unity My Ass” Clinton voters (PUMAs) in 2008. Obviously, Democrats were largely unified behind Obama that November.

nrakich: Right, and also, no one asked whether PUMA voters cost Obama that election — he won handily! So it’s clearly possible to win after a divisive primary.

In fact, according to one study, only 70 percent of Clinton voters in 2008 voted for Obama — comparable to, and even a bit lower than, the three-quarters of Sanders voters who we think voted for Clinton in the 2016 general election. So it wasn’t party unity per se that cost Clinton the 2016 election — the party was about equally united in 2008 and 2016. Instead, it was how close the election already was that made the difference. And it could come down to that again in 2020.





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