The percentage of Democrats who say they would vote for former Vice President Joe Biden Joe BidenPelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Hillicon Valley: Subpoenas for Facebook, Google and Twitter on the cards | Wray rebuffs mail-in voting conspiracies | Reps. raise mass surveillance concerns Fox News poll: Biden ahead of Trump in Nevada, Pennsylvania and Ohio MORE if the presidential race were held tomorrow slipped by 10 points after the first primary debate.

According to a Morning Consult/FiveThirtyEight poll of likely Democratic voters released on Friday, 41.5 percent said before the debates they would vote for Biden tomorrow, but 31.5 percent said the same thing after Thursday night’s debate.

The apparent decline in support comes after Biden was widely seen as having faltered, including engaging in a stark exchange with Sen. Kamala Harris Kamala HarrisHundreds of lawyers from nation's oldest African American sorority join effort to fight voter suppression Biden picks up endorsement from progressive climate group 350 Action 3 reasons why Biden is misreading the politics of court packing MORE (D-Calif.) over school busing.

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Harris herself got a nearly 9 point bump, with 16.6 percent of Democrats saying they would support her after the debate, up from 7.9 percent before the events.

Other 2020 candidates had marginal increases or decreases.

Biden defended himself Friday during a speech in Chicago, saying that “I fought my heart out to ensure that civil rights and voting rights, equal rights are enforced everywhere” and that he “never, ever opposed voluntary busing.”

Morning Consult and FiveThirtyEight surveyed, from June 19-26, 7,150 registered voters who say they are likely to vote in their state’s Democratic primary or caucus. That result has a margin of error of 1 percentage point. Then, June 27-28, 1,399 respondents who answered the first round of questioning were surveyed. That result has a margin of error of 3 percentage points.