Former President Donald Trump and President Joe Biden debate at CNN's Atlanta studios on June 27, 2024.
Washington CNN  — 

They’re not writing anything down. They’re not making any firm commitments.

But between staring into phones that started buzzing about three minutes into the debate and haven’t stopped since, several of Joe Biden’s leading possible Democratic replacements and top aides have started to think through what an unprecedented last-minute fight into the August convention might look like.

They’re already carefully monitoring their prospective opponents’ moves as they go, looking both for openings and ways to call them out for getting ahead of the president. Multiple people connected with other candidates, for example, noted the “interesting timing” of an already-scheduled fundraising appeal that Michigan Gov. Gretchen Whitmer’s PAC texted out on Friday evening that reads almost like a mission statement for her and points out how she won in her key presidential battleground state.

More than two dozen top Democratic officials, political operatives and donors tied to Biden and to many of the people most discussed as potential substitutes – many of whom asked for anonymity to discuss the most politically fraught situation most have ever encountered – say they’re terrified by nearly every scenario: Going forward with Biden, a Kamala Harris nomination, a nomination of someone else who would in that case have beaten the first Black female vice president, long nights of multiple ballots spilling ideological and personal feuds on national television, even just revelations of embarrassing details about people who have never been vetted by a national campaign.

“It would be a Category 5 hurricane,” said one top Democratic official nervous about Biden considering what would happen if the president stepped aside. “People don’t understand the sheer destruction that would be unleashed.”

To others, that stems from a prisoner’s mentality that doesn’t consider how much resistance there is to Trump.

“I think we can absolutely swap and win,” said a major Democratic donor. “If Joe Biden’s the nominee, we’re all in. If someone else is the nominee, we’re all in.”

A CBS News/YouGov poll out Sunday morning found only 55% of registered Democratic voters saying Biden should continue running, with 45% saying he should step aside. Biden campaign aides have spent the last couple of days pointing to metrics like some of their best grassroots fundraising days and a surge in job applications since Thursday.

None of the speculation matters if a president who will be three months older by the next scheduled debate doesn’t step aside. So far, he has stuck to an apologetic but defiant posture in public while in private saying he knows how bad his performance was but that he still thinks his candidacy is the only way forward.

And since he won all the primaries, he controls most of the delegates, which means that they can only vote for someone else if he decides to pull out.

President Joe Biden and First Lady Jill Biden, alongside granddaughters Natalie left, and Finnegan, second from right, make their way to board Air Force One before departing McGuire Air Force Base in Burlington, New Jersey on June 29, 2024. Biden is heading to the Camp David presidential retreat where he was expected to spend the rest of the weekend.

Democrats feeling the ground move beneath their feet

Multiple Democratic officials and operatives, some of whom are affiliated with alternatives and those who are not, rage that Biden has demonstrated too much of an ego to have bowed out before. The president’s argument that he was the Democrat best able to beat Trump, several said, has now been turned on its head and they are left feeling he’s the option least able to beat Trump.

They say the president’s inner circle who have been running the campaign and prepared him for the debate – and who told some privately ahead of Thursday night that the prep had gone well – are either not being honest or are not capable of steering him either toward an exit or a recovery. At a LGBTQ fundraiser in New York City on Friday night, one attendee said some of the conversations even turned against Jill Biden, with the deep love for her as the quirky reluctant political spouse quickly curdling into exasperation that she is not willing to make the move that would lead to them leaving the White House.

Even as minds turn to a list that includes Harris, Illinois Gov. J.B. Pritzker, Whitmer, Kentucky Gov. Andy Beshear, California Gov. Gavin Newsom, Arizona Sen. Mark Kelly, Georgia Sen. Raphael Warnock, Transportation Secretary Pete Buttigieg and even relatively new Pennsylvania Gov. Josh Shapiro and Maryland Gov. Wes Moore, none have gone public with anything but words of support for Biden. They worry about being called traitors. They worry that it might make Biden dig in more.

A debate watch party in Los Angeles on Thursday night happened to feature Harris’ husband Doug Emhoff, Pritzker, Whitmer and Beshear. There were other high-profile attendees – by a few answers in, Rob Reiner was screaming about losing and Jane Fonda had tears in her eyes, according to people in the room.

Even Barack Obama is choosing his words carefully. When asked about the debate by House Minority Leader Hakeem Jeffries at a fundraiser for House Democrats, he said Biden has “the values that reflect the best in America,” but politics is a “team sport,” with the president as “the captain.” He added that getting Jeffries to be speaker is “probably the most important thing we can do for the Biden reelection campaign as well.”

Biden campaign aides dismiss not only the possibility that he will drop out, but that anyone could actually do better, or go up against Trump with a list of supporters that runs from progressive icon Rep. Alexandria Ocasio-Cortez to conservative GOP former Georgia Lt. Gov. Geoff Duncan.