Massachusetts Senator Elizabeth Warren has participated in three Democratic debates – and has been seen as the winner in all three. In last Thursday’s debate, the first one where she shared the stage with Vice President Joe Biden, Democratic primary voters gave her the edge over Biden in the latest Economist/YouGov Poll, with no other debate participant named as the best in the debate by more than 8 percent of Democratic voters.

Democratic voters had expected Warren to do best in this debate. Warren continues to be the most popular of the current Democratic candidates among Democratic voters. She receives the highest favorable rating (76%) overall, and the lowest unfavorable rating (16%) of the 10 candidates who participated in the debate.

Vermont Senator Bernie Sanders and Biden have favorable ratings of 70 percent and 69 percent, respectively, with those same Democratic voters, but more than one in four have unfavorable ratings of each of them. In addition, fewer than one in 10 Democratic voters say they would be disappointed if Warren became the nominee. The nomination of all the other debate participants would disappoint between 12 percent and 22 percent of potential Democratic voters.

More importantly, perhaps, in an election where Democratic voters prioritize electability over issue agreement (65% to 35%), as many Democratic voters now see Warren as just as likely to defeat President Donald Trump as Biden. That’s the first time that’s happened.

A majority also believes Sanders can win, and a smaller share (though still a plurality) say the same about California Senator Kamala Harris. As many say South Bend Mayor Pete Buttigieg can win as say he can’t. None of the other debate participants come close to passing the electability threshold that Democratic voters say they are most interested in.

For most of the candidates, the debate changed little in overall opinion. But it did solidify the “top 10.” More Democratic voters say they are considering voting for each of the debate participants than say they are considering any of the others. Hawaii Representative Tulsi Gabbard’s 6 percent on this question is the highest for any of the non-participants. All the participants are in double digits.

Presidential politics

Biden continues to hold a lead when Democratic voters are asked their first choice. Warren tied him in last week’s poll for the first time, but this week’s results on this question came back to match previous readings.

Biden benefits from big leads with black voters and senior citizens. Warren is ahead with liberals, while she and Sanders are essentially even and ahead of Biden among Democratic voters under 30. Warren also does well with voters who are paying a lot of attention. One in four of them say Biden is their first choice; one in four say Warren. Among those currently paying little or no attention, 27 percent favor Biden, 17 percent Sanders, and only 9 percent name Warren.

The three Democratic front runners (as well as Trump) are all in their 70s, not the most optimal age to serve as president, according to this week’s poll. Democratic primary voters – and all voters – prefer a younger president. Only 4 percent say the 70s is the ideal age to be President. Biden and Sanders, if elected, would turn 80 in the White House. That worries 39 percent of Democratic voters, who believe it might be too difficult for someone that old to do the job. However, more than a quarter who think this are currently supporting Biden or Sanders.

Former President Barack Obama is extremely popular with Democratic voters: 87 percent of them hold a favorable view of him, while just 12 percent are unfavorable. There is no consensus about which of the current Democratic candidates is most like Obama: 23 percent of Democratic primary voters say it’s Biden, Obama’s running mate, and 10 percent say it’s Buttigieg, giving him second place.

For most candidates, their debate performance had little impact on their overall popularity. But for two, Democratic opinion changed afterward, not necessarily in first-choice support, but in positive ratings.

Former Texas Representative Beto O’Rourke called for a mandatory buyback of assault weapons like the AR-15 (something 71 percent of Democratic primary voters in this poll support). His favorable ratings among those votes went up to 62 percent from 56 percent last week.

On the other hand, former Housing and Urban Development Secretary Julian Castro was criticized for his attacks on Biden, particularly when he talked about Biden’s age. Castro’s favorable rating dropped 12 points after the debate.

See the full toplines and tables results from this week's Economist/YouGov poll.

Related: Despite low unemployment, America's economic worries continue

Image: Getty