Above all, Joe Biden's allies wanted him to demonstrate strength and energy on the debate stage to help put to rest questions about the 81-year-old Democrat's physical and mental acuity.

But on the biggest stage in U.S. politics on Thursday night, Biden did not meet their modest expectations.

And by the end of the 90-minute showdown, the Democratic president's allies — party strategists and rank-and-file voters alike — descended into all-out panic following a debate performance punctuated by repeated stumbles, uncomfortable pauses, and a quiet speaking style that was often difficult to understand. Publicly and privately, Democrats questioned whether the party could or should replace him as the party's presidential nominee against the 78-year-old Republican former President Donald Trump this fall.

"I'm not the only one whose heart is breaking right now. There's a lot of people who watched this tonight and felt terribly for Joe Biden," former Democratic Sen. Claire McCaskill said on MSNBC. "I don't know if things can be done to fix this."

For now, the biggest question for Biden is whether the damage is permanent. Many voters have not yet tuned into an election that's still more than four months away. The president and his allies are sitting on millions of dollars that have yet to be spent on advertising and swing state infrastructure. And there's precedent for recovering from rough debate performances, including Barack Obama's rebound from an uneven encounter with Mitt Romney in 2012. Democrat John Fetterman went on to defeat a Republican rival in 2022 after struggling through a debate several months after experiencing a stroke.

Biden's gamble

Biden's 2024 reelection campaign was always based on a gamble that voters would ultimately support an 81-year-old lifelong politician with weak approval ratings in a rematch that few Americans want. Despite such liabilities, Biden's team insisted that he was uniquely positioned to stop Trump from returning to the White House — just as he did four years ago.

They have long predicted that Biden's winning political coalition would eventually embrace the Democratic president after being sufficiently reminded of Trump's chaotic leadership. But there were little signs of such confidence in the wake of Biden's underwhelming debate performance.

"It was a slow start. That's obvious to everyone. I'm not going to debate that point," Vice President Kamala Harris said on CNN after the debate. "I'm talking about the choice in November. I'm talking about one of the most important elections in our collective lifetime."

Biden's surrogates were slow to enter the post-debate spin room in Atlanta. And when they finally emerged, they largely avoided questions from the press. Instead, they railed against Trump's long list of falsehoods during the debate. Among other things, Trump didn't disavow those who attacked the Capitol on Jan. 6, 2021.

California Gov. Gavin Newsom, a potential future presidential candidate who was Biden's most prominent surrogate in the Atlanta spin room, urged Democrats not to panic.

"I think it's unhelpful. And I think it's unnecessary. We've got to go in, we've got to keep our heads high," Newsom said in an interview on MSNBC. "We've got to have the back of this president. You don't turn back because of one performance. What kind of party does that?"

Signs of anxiety

Still, signs of anxiety were apparent as Democrats began to openly encourage the party to find an alternative to Biden. Some party officials pointed to a social media post from former Obama campaign aide Ravi Gupta.

"Every Democrat I know is texting that this is bad," Gupta wrote on X. "Just say it publicly and begin the hard work of creating space in the convention for a selection process. I'll vote for a corpse over Trump, but this is a suicide mission."

Under current Democratic Party rules, it would be difficult, if not impossible, to replace Biden as the party's nominee without his cooperation or without the party officials being willing to rewrite its rules at the August national convention.

The president won the overwhelming majority of Democratic delegates during the state-by-state primary process. And party rules state, "Delegates elected to the national convention pledged to a presidential candidate shall in all good conscience reflect the sentiments of those who elected them."

But DNC rules don't have the same strict "faithless delegate" rules that the RNC does, which ignore votes against in violation of a delegate's pledged position.

Republicans, meanwhile, were giddy about Biden's lackluster performance. But Trump's co-campaign chief dismissed chatter about whether Democrats would try to nominate someone other than Biden.

"There's so many political experts on X, so we'll hear a lot from them, I'm sure, in the next few days because they've all run so many campaigns," Chris LaCivita said sarcastically. "But the only way that happens is if Joe Biden voluntarily steps down, and he's not going to do that."

Thursday's debate may be imprinted on voters' minds for the foreseeable future with Biden and Trump not scheduled to meet on the debate stage again for another 75 days.

LaCavita said Trump would be at the next debate "with bells on." Biden campaign spokesman Kevin Munoz confirmed that Biden would also attend the rematch.

But privately, Biden advisers suggested that the campaign was never going to be won or lost in one rally, conversation or debate. They pointed to plans to maintain an aggressive schedule in the weeks and months ahead.

On Friday, Biden was scheduled to campaign in North Carolina while Harris was in Nevada.

Still, Biden supporters struggled to find any hope in the immediate aftermath of the debate.

"That was the worst performance in the history of televised presidential debates," Tim Miller, a former Republican strategist-turned ardent Biden supporter, said in the spin room, shaking his head in disbelief.