Top national Democrats are coming forward with their concerns about President Biden’s candidacy nearly a week after his poor showing at a debate against former President Trump.

Hours after former Speaker Nancy Pelosi, D-Calif., admitted on MSNBC that discussions about Biden’s mental health are "legitimate," several high-profile figures on the left went even further with their thoughts on the president’s fitness for office.

Former Obama administration Housing and Urban Development Secretary Julian Castro told the network a short while later, "[I] believe that another Democrat would have a better shot at beating Trump. ... I think Democrats would be well to find another candidate."

Adam Frisch, who is running to flip Rep. Lauren Boebert’s current Colorado district from red to blue, came out with his own statement on Tuesday in which he called on Biden to step aside.

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Nancy Pelosi and Joe Biden split image

Former House Speaker Nancy Pelosi conceded that questions about President Biden's and former President Trump's fitness for office are "legitimate" (Getty Images)

"It has been clear to me for some time, and the debate only reinforced it, neither candidate should be running for president," Frisch said. "We deserve better. President Biden should do what’s best for the country and withdraw from the race."

And Rep. Lloyd Doggett, D-Texas, became the first sitting House Democrat to outright call for Biden to end his campaign.

"My decision to make these strong reservations public is not done lightly nor does it in any way diminish my respect for all that President Biden has achieved," Doggett said in a statement. 

"Recognizing that, unlike Trump, President Biden’s first commitment has always been to our country, not himself, I am hopeful that he will make the painful and difficult decision to withdraw. I respectfully call on him to do so."

Hours later, a staunch Biden ally, Sen. Pete Welch, D-Vt., was asked on MSNBC whether the door should be left open to other Democrat candidates.

"It is open, let's be candid," Welch said. He added, referring to the debate, "What we saw can't be unseen. That was an unsteady performance, and it raises questions about his physical condition."

Welch said Democrats beating Trump was "more important than anything" and that Biden's campaign was reviewing "how to proceed."

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Lloyd Doggett

Rep. Lloyd Doggett is the first sitting House Democrat to call on Biden to step aside. (Alex Wong/Getty Images)

Another top Biden ally, Rep. James Clyburn, D-S.C., did not go so far as to call for Biden to step aside, but he told MSNBC that he would support Vice President Harris for president if Biden did as well.

The outpouring of doubt comes after Pelosi told "MSNBC Reports," "I think it's a legitimate question to say, ‘Is this an episode or is this a condition?’ When people ask that question, it's completely legitimate of both candidates."

She also lauded Biden's record over the last four years, but her comments are a damning acknowledgment of growing public concern about the 81-year-old president's fitness for office.

Biden has not indicated he would step aside. His campaign also indirectly attempted to refute concerns by announcing a $264 million fundraising haul for the second quarter of 2024, including $127 million that came in during June.

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trump and biden

The concerns stem from Biden's performance at last week's debate. (Andrew Harnik/Getty Images)

But questions have mounted since his Thursday night debate performance, where he spoke with a hoarse voice, reportedly due to a cold, and stumbled over his own answers several times during the prime-time event. Viewers also observed him appearing tired and noticeably less sharp than he looked the last time he faced Trump in 2020.

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A new CBS News and YouGov poll released over the weekend showed nearly three-quarters of Democrat voters believe Biden does not have the cognitive health to serve as president.

A USA Today/Suffolk University poll released Monday shows Trump leading Biden 41% to 38% among nationwide voters.