WASHINGTON -- U.S. President Joe Biden has privately acknowledged that the next stretch of days are critical to whether he can save his reelection bid for president, making clear to an ally Tuesday that he understands what would prompt him to accept: 鈥淚t鈥檚 just not working.鈥

鈥淗e sees the moment. He鈥檚 clear-eyed,鈥 this person told CNN.

There is no ambiguity for the president about what potential series of events in the coming weeks would ultimately prompt him to acknowledge that his attempt to make amends for last week鈥檚 disastrous debate on CNN aren鈥檛 working, according to this ally.

It would be a scenario in which 鈥渢he polls are plummeting, the fundraising is drying up, and the interviews are going badly,鈥 they said. 鈥淗e鈥檚 not oblivious.鈥

In response to a request for comment, White House spokesman Andrew Bates said that 鈥渋t is false to suggest there is any openness to ending the campaign.鈥

In the days since Biden鈥檚 stunningly halting debate showing, Democrats across the country have expressed grave concern. Some elected officials have even begun to publicly call on Biden to drop out for the good of the party.

reported separately on Wednesday that Biden acknowledged that he may not be able to save his campaign if he does not perform well in public events over the next several days. The White House and Biden鈥檚 campaign have denied that reporting.

In Tuesday鈥檚 private conversation, Biden was also 鈥渃hastened鈥 as he 鈥渂lamed himself鈥 鈥 not his staff 鈥 for the debate performance.

鈥淗e said: 鈥業 have done way too much foreign policy,鈥欌 this person said. 鈥淗e said to me: 鈥業 have over done it. I did too much travel. I did too much back and forth. I did too much time change. I had a cold. That was a mistake.鈥欌

Biden was referring to his back-to-back trips to France and Italy right before the debate, even though he had nearly two weeks between his return on June 15 from Italy for the G7 meeting and the debate on June 27, according to a CNN review of his schedule.

But as much as Biden suggested that the jet lag and exhaustion from his travels had been detrimental, he also signaled that he wanted to put the debate in the rearview mirror in his conversation with the ally.

And at one point in their conversation, Biden asked this person for advice 鈥 and then there was silence, the person told CNN, as the president waited for input.

But even in the highest levels of Biden鈥檚 own administration, serious doubt is starting to set in about whether the president will be able to ride this one out.

A senior Biden administration official speaking on the condition of anonymity told CNN that they personally view the current trend of the gradual erosion of support for Biden among Democrats as 鈥渨aves crashing into the shore.鈥

鈥淔irst it鈥檚 the donors. And then it鈥檚 elected officials. Now it鈥檚 going to be polling. It just breaks down the resistance,鈥 they said. 鈥淭here鈥檚 a group that started small and is getting bigger and bigger.鈥

The senior official said Biden would likely need some time to 鈥渞econcile鈥 the 鈥減ull and the push鈥 as he navigates and digests the coming days and hears from those who believe he should dig in, as well as others who will tell him to step aside for the good of the party. Two sitting House Democrats have so far called on the president to abandon his reelection bid.

Where Biden鈥檚 family will end up is an important unknowable at the moment, the official added: 鈥淚 can鈥檛 tell you how defiant the family is going to be, which is a big factor.鈥

The president said at a fundraiser in Virginia Tuesday night that going on two significant foreign trips right before the debate had been a bad idea.

During that fundraiser, Biden joked that he 鈥渁lmost fell asleep onstage鈥 during the debate last week and blamed his poor performance on his grueling travel schedule, according to pool reports.

鈥淚 decided to travel around the world a couple of times 鈥 shortly before the debate 鈥 I didn鈥檛 listen to my staff 鈥 and then I almost fell asleep onstage,鈥 Biden said during the fundraiser. The remark was met with brief laughter from those in attendance, according to a recording of the president鈥檚 remarks.

Multiple reporters who were in the room said that they believed the 鈥渇ell asleep鈥 line appeared intended to be a joke and that Biden was trying to make light of the situation in a self-deprecating way, but it did not land, in their view.

Since the debate, Biden has faced one of the toughest stretches of his presidency and his reelection campaign is reeling. Campaign officials are scrambling to calm donors who were shocked by Biden鈥檚 performance. The White House announced that Biden is expected to meet with Democratic governors and congressional leaders Wednesday after some demanded a meeting with the president. Some officials have been turned off by the Biden campaign鈥檚 dismissiveness over their concerns about the president鈥檚 health. On Tuesday, a Democratic member of Congress became the first to publicly ask Biden to drop out of the race.

Biden and Vice President Kamala Harris called into the Biden campaign鈥檚 all-staff call on Wednesday, a source familiar with the call said.

The source described it as a 鈥減ep talk鈥 in which Biden and Harris detailed the stakes of the election.

Biden reiterated that when one gets knocked down, they need to get back up, a familiar refrain from the past week, and said, 鈥淟et鈥檚 go win this,鈥 the source said.

Biden 鈥渁cknowledged the tough past few days and said unequivocally to his team he is running for reelection and he is going to beat Donald Trump,鈥 another source familiar with the call told CNN.

鈥淚鈥檓 in this race to the end and we鈥檙e going to win because when Democrats unite, we will always win. Just as we beat Donald Trump in 2020, we鈥檙e going to beat him again in 2024,鈥 Biden told his team, according to that source.

Harris, who is dismissing calls to replace Biden, told the team that she will follow Biden鈥檚 lead.

鈥淲e will not back down. We will follow our president鈥檚 lead. We will fight, and we will win,鈥 Harris said, according to the source.

Biden concluded, according to the source: 鈥淭here is no one I鈥檇 rather be in this battle with than all of you. So, let鈥檚 link arms. Let鈥檚 get this done. You, me, the vice president. Together.鈥

White House chief of staff Jeff Zients held a less than 10-minute all-staff call to encourage his team to tune out the chatter and press ahead with their work even as questions about Biden鈥檚 candidacy swirl, one source who participated in the call said.

Keep your 鈥渉eads down, get things done, execution, execution, execution. Second, heads up 鈥 there鈥檚 so much to be proud of and there鈥檚 so much more we will do together under this president鈥檚 leadership,鈥 Zients said, according to the source.  鈥淭his team can do anything and don鈥檛 forget to have each other鈥檚 backs.鈥

Zients, who did not take questions on the call, told staff that the 鈥渟trong campaign team鈥 will focus on the reelection efforts while staff at the White House should focus on executing the work of the administration, the source said.

Zients decided to convene a call with White House staff in part to acknowledge the challenges of the post-debate period, a White House official said. In a previous meeting with senior staff on Friday, Zients and senior adviser Anita Dunn spoke about the president鈥檚 debate performance and the expected difficult period ahead, the official said.

On Wednesday鈥檚 call, Zients echoed the president, declaring, 鈥淲hen you get knocked down, you get back up.鈥

鈥淭hat鈥檚 what he is doing and that鈥檚 what we all need to do,鈥 he said.

CNN鈥檚 Betsy Klein, Arlette Saenz and Michael Williams contributed to this report.