A new 2020 Democratic primary poll shows Warren surging alongside fellow frontrunners Biden and Sanders

• A new 2020 Democratic primary poll from ABC News and The Washington Post shows a slight dip in Joe Biden's and Bernie Sanders' numbers, with the former vice president still in the lead with 27%, and the senator as runner-up with 19%.
• Senator Elizabeth Warren comes in third with 17%, up six points from the last ABC/Post joint poll.
• Senator Kamala Harris saw a slump to 7%, down four points since the July 1 poll.
• Mayor Pete Buttigieg maintained a steady 4%, and candidates that fell below him were not included in the results, which precedes the next Democratic debate on September 12 in Houston, Texas, hosted by ABC and Univision.
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Ahead of Thursday's Democratic debate in Houston, Texas, host ABC News released a new poll of primary candidate preference among Democrats. It shows former vice president Joe Biden in the lead with 27%, followed by Senators Bernie Sanders and Elizabeth Warren at 19% and 17%, respectively. Other candidates trailed by 10% or more.

Produced by Langer Research Associates for ABC News and The Washington Post, the poll compares preferences from September 5 to those on July 1, days after the first 2020 Democratic debates. It surveyed 1,003 adults by phone. Both Biden and Sanders saw a slight slump since then, with the former losing two points and the latter losing four.

Warren's numbers increased by a striking six points, the only candidate to gain a percentage. Senator Kamala Harris fell from 11% to 7%, and Mayor Pete Buttigieg remained steady with an unchanged 4%. Representative Beto O'Rourke and entrepreneur Andrew Yang both received 3%, and all other candidates fell under 1%.

Ten candidates will take the stage on Thursday for the third round of the Democratic primary debates, hosted by George Stephanopoulos on ABC News and Univision. Those who qualified for the debates but not for the ABC/Post poll results are Senators Cory Booker and Amy Klobuchar and former Secretary of Housing and Urban Development Julián Castro.

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If narrowed to those who are currently registered to vote, ABC News reports Klobuchar and Representative Tulsi Gabbard both reach 2%, and Biden and Warren gain two points and one point, respectively.

Warren's gains were in the northeast, where the Massachusetts senator is from, in urban areas, and among liberals. Harris lost 10 points among seniors, who lean toward Biden. But a full 55% of those surveyed say they would consider switching their candidate preference.

Biden is the only candidate with a majority of his current supporters pledging to see their support through to the primary. 64% say they'll definitely support him, as compared to 34% of committed voters for all the other Democratic candidates combined. In terms of who could beat President Donald Trump, Biden also reigns supreme, with 42% picking him as the most likely to win in a general election, compared to 14% for Sanders and 12% for Warren.

However, while primary polls have historically been good predictors, even this early out, general election polls are not. Being able to beat Trump is important to a majority of Biden and Warren supporters, whereas Sanders supporters ranked "closest to me on issues" as more important. When asked if Biden was "the best president for the country," his numbers dropped to 23%, with Warren at 19%, and Sanders at 16%.

Biden's support stems largely from black voters, who favor him at 44%, double his support from white and Hispanic voters. He also leads moderates by 33%, but has comparable numbers to Sanders and Warren among liberals. In terms of age, Biden has courted seniors, whereas voters aged 18 to 29 prefer Sanders by 41 percent.

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