Biden dialled in to a call with worried members of his campaign team, telling them he wasn't going anywhere, according to two sources familiar with the call.
"I am running," Biden said, adding he remained the Democratic Party leader and wasn't being pushed out of the race against Republican Donald Trump, one source said.
The president will also meet with Democratic governors on Wednesday night (local time) to reassure them he is up to the job of standard-bearer for the party after the faltering debate performance, when he mumbled under his breath, lost his train of thought at times and at one point, talked of beating Medicare. Some governors will attend virtually.
Asked earlier on Wednesday if Biden, 81, was considering stepping down, White House Press Secretary Karine Jean-Pierre said: "Absolutely not."
Soon after she spoke, two national polls suggested Biden's chances against 78-year-old Trump - who rattled off a series of well-worn falsehoods during the debate - had deteriorated since the debate. A Wall Street Journal survey found Trump beating Biden by a margin of 48% to 42%, up one percentage point, while a New York Times/Siena poll found Trump's lead over Biden had widened by three points to 49% to 43%.
House Democrats are holding a call at 5pm on Wednesday (local time) on the subject, and a second Congressional Democrat, Arizona's Raúl Grijalva, called for Biden to drop out of the race. Other Democrats concerned about Biden's viability in the November 5 election will be closely watching an interview with ABC News expected to be broadcast this weekend.
Biden spoke to Representative Hakeem Jeffries, the minority leader in the House of Representatives, on Tuesday, and Senator Chuck Schumer, the majority leader in the Senate, on Wednesday, a White House official said. He also spoke with House Democrat Jim Clyburn on Wednesday, whose office said afterward they had a long, private conversation.
Clyburn - a kingmaker of sorts within the Democratic Party and who was instrumental in Biden's 2020 win - told CNN on Wednesday that the party should hold a "mini-primary" if Biden steps aside, the first senior party member to talk publicly about how replacing Biden as a candidate could work.
Clyburn, who said on Tuesday that he would back Vice President Kamala Harris as the presidential candidate if Biden were to depart, added: "If she were to be the nominee, we need to have a running mate and a strong running mate. And so all of this would give us an opportunity, not just to measure up who would be good to be at the top of the ticket, but also who would be best in second place."
Democrats raised fresh concerns about Biden on Tuesday, with one House member calling for him to drop out and former Speaker Nancy Pelosi, a longtimeBiden ally, saying it was legitimate to ask whether Biden's performance in Atlanta last week was an "episode" or a condition.
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The president has said he was tired after two foreign trips and the White House has said he had a cold. His campaign has held damage control calls with donors, and Biden has shown no signs so far abandoning his quest for a second term.
White House chief of staff Jeff Zients held a call with demoralized White House staff on Wednesday as well, acknowledging that it had been a challenging few days while stressing that the Biden team had a record to be proud of and more work to do.
A handful of governors are potential rivals to Biden if pressure for him to step aside were to increase, but many of them also speak on Biden's behalf on the campaign trail.
Harris is the likely successor if Biden does step aside, multiple sources told Reuters. However Michigan Governor Gretchen Whitmer, California Governor Gavin Newsom, Illinois Governor J.B. Pritzker, Pennsylvania Governor Josh Shapiro and Kentucky Governor Andy Beshear have all been mentioned as possible replacements to Biden if he decided to bow out as the 2024 candidate.
A video created for Harris's failed 2020 presidential bid, that shows her grilling Republicans including former Attorney General Bill Barr and then-Supreme Court nominee Brett Kavanaugh, circulated in Democrat donor circles on Wednesday.