a fuzzy podiums with blue dots behind it

UPDATED Mar. 16, 2020, at 12:58 PM

Who Won The Biden-Sanders Debate?

We partnered with Ipsos to poll voters before and after the candidates took the stage.

On Sunday night, former Vice President Joe Biden and Sen. Bernie Sanders challenged each other’s records at the debate hosted by CNN in Washington, D.C., but it was the coronavirus that dominated both the debate and headlines. We once again partnered with Ipsos to track how the debate affects likely primary voters’ feelings about the candidates. The FiveThirtyEight/Ipsos poll, conducted using Ipsos’s KnowledgePanel, interviews the same group of voters twice, once on either side of the debate, to capture both the “before” and “after” picture.

Who won the debate?

The debate doesn’t seem to have been much of a game-changer. In terms of raw debate grades — respondents graded candidates on a four-point scale (higher scores are better) — Biden did score slightly higher than Sanders, but respondents rated both of their performances pretty highly and both were viewed pretty favorably by respondents before the debate.

How viewers graded the candidates

CandidatePre-debate favorabilityDebate performance
Joe Biden69.4%3.3
Bernie Sanders62.63.1

How the race changed

Who gained (and lost) support

Share of respondents who are considering voting for each candidate

Before debateAfter debate

Respondents could pick multiple candidates or ‘someone else.’

Biden picked up a little over 3 points in potential support while Sanders experienced a 2 point decrease, but neither change was particularly big, unlike some of the gains and drops we saw in previous debates.

The popularity contest

Candidates' favorable and unfavorable ratings among likely primary voters

Before debate
After debate

We also asked likely Democratic primary voters how favorably they felt about each candidate both before and after the debate, and, notably, both Biden and Sanders had very high favorability ratings going in. They both managed to make a positive impression last night, too. Sanders’s net favorability (favorable rating minus unfavorable rating) rose almost 4 points and Biden’s rose 1 point.

Our latest coverage

Who voters think can beat Trump

Respondents’ estimates of the likelihood, from 0 percent (impossible) to 100 percent (certain), that each candidate would beat Trump if they were the Democratic nominee

Joe Biden
Bernie Sanders

Finally, we asked respondents to estimate each Democrat’s chances of defeating President Trump, from 0 percent (no chance) to 100 percent (certain to win). Going into the debate, voters thought Biden was the most likely to win in the general election. That was true after the debate as well. Respondents’ average rating of Biden’s and Sanders’s ability to defeat Trump was mostly unchanged.

Respondents’ average rating of candidates’ chances vs. Trump

CandidatePre-debate averagePost-debate averageDiff.
Joe Biden66.767.3+0.6
Bernie Sanders54.454.8+0.4