Nearly a week after President Biden's disastrous performance in a presidential debate, multiple current and former House Democrats are signaling they would back Vice President Kamala Harris as his successor if the 81-year-old leader chooses to step aside.

Rep. Summer Lee, D-Pa., a member of the House's progressive "Squad," joined radio show "Mornings with Zerlina" on Wednesday, warning Democrats — and likely, by extension, President Biden — they are running out of time to decide whether to change course.

"If our president decides this is not a pathway forward for him, we have to move very quickly. There’s not going to be time for a primary. That time is past," Lee said. "The vice president is the obvious choice. She’s sitting right there."

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Vice President Kamala Harris speaks during an event at Discovery World.

Vice President Kamala Harris is seen as a likely successor if President Biden steps aside. (AP Photo/Morry Gash)

Lee also warned of the political ramifications of side-stepping Harris while pointing out the high voter turnout rates among Black women.

"We’re so willingly going to push aside an entire demographic, and I think that it would be very dangerous to do that, personally," she warned.

It comes just a day after Rep. Jim Clyburn, D-S.C., a longtime Biden ally whose support was critical to Biden clinching the 2020 Democratic presidential nomination, stopped short of airing concerns about the president's viability. He added, however, that he would support Harris as the nominee if Biden did drop out.

"I want this ticket to continue to be Biden-Harris," Clyburn said on "MSNBC Reports." "This party should not, in any way, do anything to work around Ms. Harris. We should do everything we can to bolster her whether she's in second place or at the top of the ticket."

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Rep. Summer Lee speaking at microphone

Rep. Summer Lee, D-Pa., argued in favor of Harris on Wednesday. (Getty Images)

Former Rep. Tim Ryan, D-Ohio, who challenged Biden for the 2020 presidential nomination, also wrote an op-ed in Newsweek, "Kamala Harris Should Be the Democratic Nominee for President in 2024."

White House press secretary Karine Jean-Pierre answered speculation about Harris on Wednesday by insisting Biden would not drop out and declined to get into details about their one-on-one lunch earlier in the day.

"One of the reasons why he picked the vice president … is because she is indeed the future of the party. And he's very proud to have partnered with her and continue to partner with her and delivering an unprecedented record for the American people," Jean-Pierre said.

Questions about Biden's physical and mental condition were brought to the forefront during Thursday's debate in Atlanta. 

The dam broke on Tuesday afternoon when Rep. Lloyd Doggett, D-Texas, became the first sitting House Democrat to call for Biden to pull out of the race.

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Rep. Jim Clyburn raises hands during speech

Rep. Jim Clyburn, D-S.C., also said Harris should be Biden's successor.  (Brian Stukes/Getty Images)

Hours later, Reps. Jared Golden, D-Maine, and Marie Gluesenkamp Perez, D-Wash., two of the most vulnerable Democrats this election cycle, came out and said Biden would likely lose to Trump.

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"He is absolutely not dropping out," a Biden campaign spokesperson told Fox News Digital.

If he did, however, Harris' supporters have pointed out she would inherit the massive $240 million Biden-Harris campaign war chest.

Other names who have been floated as possible replacements for Biden are California Gov. Gavin Newsom, Michigan Gov. Gretchen Whitmer and Illinois Gov. J.B. Pritzker, among others.