Almost half, or 47%, of Democratic or Democratic-leaning voters who said they watched most of the debate or paid attention to news stories about them said Harris did the best job, according to the Quinnipiac poll.
Black voters' support for Biden, 76, fell from 40 percent to 20 percent after the debate, according to a new Reuters/Ipsos poll.
An impact is apparent: among the half of leaned Democrats who did not watch either of the two nights of debates, just 5% support Harris for the nomination. The polls show a steep gain for Senators Kamala Harris and Elizabeth Warren.
Biden made the remarks Harris was referring to last month, at a fundraiser in New York City, where he reminisced about bygone days when politics was characterized by a higher level of civility, citing his ability to get along with two segregationist senators despite their differences as an example. Biden isn't the only one dropping in the polls. The poll surveyed 554 Democrats and Democratic-leaning voters nationally and had a margin of error of five points.
The first Democratic presidential debate appears to have shaken up the 2020 race - at least for now. "There are other red flags for him in areas where he still leads, including double-digit drops among Democrats and Democratic leaners who view him as the best leader, or as the best candidate to defeat President Trump in 2020", said Quinnipiac Polling Analyst Mary Snow.
As other polls have found nationally, health care is the most important issue that would affect vote (29%) followed by climate change (18%). Harris gained 13 points and Warren's support dipped by a point.
In a statement to CNBC, McInerney said, "I had actually let the campaign know I'd pulled back my support of Biden for now". But among women, Harris has a slight edge with 24 percent to Biden's 22 percent.
The survey polled 500 people who indicated they'd attend the Democratic caucus in Iowa and has a margin of error of +/- 4.4 percentage points.
In a separate show-of-hands question, all but one candidate raised their hands when asked-if elected-if they would decriminalize illegal border crossings. Those with no opinion dropped sharply, 35% in April compared with 19% now (and 6% when the full list is read).