President Biden’s decision to pursue a second term crystallized during the 2022 Thanksgiving holiday, as he gathered on Nantucket island with his large family to discuss his political future.

At the time, the choice in some ways seemed straightforward: better-than-expected results in the midterm elections had buoyed the incumbent and silenced many of his doubters, he had successfully enacted an ambitious legislative agenda and he felt strong and healthy days after celebrating his 80th birthday.

Now, after a debate performance where his stumbles and meandering responses sent shock waves through the Democratic Party, Biden’s enormously consequential decision to run as an 81-year-old after initially saying he would be a transitional figure has come under harsher scrutiny, raising fresh questions about his small circle of advisers and the Democratic leaders who facilitated his unprecedented push to remain in office until age 86.

“I think there’s real consternation, not only among his inner circle, but in the family,” said Chris Whipple, author of “The Fight of His Life: Inside Joe Biden’s White House.” “Everybody’s wondering, ‘What happened, and can this be fixed?’”

Driving the Democratic spasm of doubt and anxiety is the prospect that Donald Trump, whom Democrats see as a dishonest, anti-democratic demagogue, now appears to have at least a reasonable chance of winning. More than at any other time in his presidency, Biden’s decision to pursue another term - and his ability to carry out his duties for another four years - faces a torrent of public questioning.

In the hours since the debate, Biden and his top officials have sought to reassure donors that he is staying in the race and is capable of doing the job. People familiar with the fundraising operation say no major donors have pulled support, and the campaign touted raising more than $27 million from the debate day through Friday evening.

Biden seemed to quell the panic at least slightly with a fiery post-debate rally on Friday in Raleigh, N.C., where he addressed the anxiety over his age while signaling that he was not rethinking his decision to run.

“I know I’m not a young man, to state the obvious,” Biden said, acknowledging publicly for the first time that his speech, gait and debating skills are all showing signs of age. But he added, “I give you my word as a Biden: I would not be running again if I didn’t believe with all my heart and soul I can do this job.”

For most of his adult life, Biden has undergone grueling decisions every four years about whether to run for president, holding prolonged discussions with family and friends about pursuing the nation’s highest office.

Despite voter concerns about his advancing age, Biden’s choice to run a final race in 2024 was in some ways easier than his previous such decisions. He was an incumbent, after all, and had enjoyed a record of unexpected legislative success while rebuilding global coalitions he deeply believed in.

His family was on board, most crucially his wife Jill and his sister Valerie Biden Owens. He viewed himself as the best positioned to compete against Trump, whose political resurgence was worrying many Democrats.

“If Trump wasn’t running, I’m not sure I’d be running,” he told Democrats at a Boston fundraiser last December. And asked by Time magazine in May if he ever considered stepping aside due to his age, he replied, “No, I didn’t.”

Just two years earlier, Biden had envisioned himself as a temporary steward of a Democratic Party that was nurturing a new and more diverse generation of leaders. “I view myself as a bridge, not as anything else,” a 77-year-old Biden said in March 2020.

But shortly after he turned 80 on Nov. 20, 2022, making him the first octogenarian in the White House, Biden decided the bridge would be much longer than many anticipated. He would run for reelection, casting his presidency not as a transition, but as a transformational era in and of itself.

There were always warning signs. A Washington Post-ABC News poll in September 2022 showed that 56 percent of Democrats and Democratic-leaning Independents said the party should pick someone else as their nominee.

Republicans were already circulating videos of Biden looking confused or seeming to stumble over his words or his feet, often taken out of context. Kevin O’Connor, Biden’s physician, observed that the president’s gait seemed stiffer, while also saying he was more than capable of serving as president. And a second presidential run would clearly be more physically taxing than in 2020, when the coronavirus pandemic confined Biden to his home for long stretches.

Amid this uncertainty, the November 2022 congressional midterms instantly reshaped the dynamic in Biden’s favor, as Democrats defied widespread predictions of a “red wave” by retaining control of the Senate and keeping Republicans to a razor-thin majority in the House. To many Democrats, it suddenly seemed the party could do quite well with Biden as their leader.

“My intention is that I run again,” Biden told reporters a day after the midterms. “But I’m a great respecter of fate. And this is, ultimately, a family decision.”

The decision was also heavily influenced by a tight circle of longtime advisers - some of whom still resented top Democrats who had sidelined Biden for Hillary Clinton in 2016. His victory in 2020, coming after many of those same Democrats wrote him off due to poor showings in the early primary states, only increased his resolve to rely on his own instincts and the counsel of his family members.

Jill Biden was especially supportive of a reelection bid, and in campaign’s early days was blunt in characterizing the election as a choice between “corruption and chaos” and stability. His other family members, including his son Hunter and grandchildren, were also in favor, according to people familiar with their thinking.

“He’d spent his whole life trying to get there,” Whipple said. “He was certainly not going to walk away from the opportunity to fulfill the work he’d started in his first term. And I think that’s just the nature of people who reach that job.”

Equally important, the Democratic Party appeared to make a collective, if informal, decision not to challenge Biden, with the exception of a short-lived bid by Rep. Dean Phillips (Minn.). Unlike other campaigns, the party’s left flank failed to put forth a charismatic challenger such as Sen. Bernie Sanders (I-Vt.), in part because many left-leaning Democrats grudgingly appreciated some of Biden’s progressive accomplishments.

Democratic governors with star power, like California’s Gavin Newsom and Michigan’s Gretchen Whitmer, initially appeared to be running shadow campaigns, but the midterms ended such efforts. Some have suggested that former president Barack Obama could have prevailed on Biden not to run had he chosen, but the two men’s relationship had been strained since Obama discouraged Biden from running in 2016 in favor of Clinton, who then lost to Trump.

When Biden officially announced his reelection on April 25, 2023, doubts still simmered. A poll from the Associated Press showed that only 47 percent of Democrats wanted him to run again. In the 24 hours after his announcement - typically a moment of surging excitement that fuels campaign donations - the result was “extremely underwhelming,” The Post reported at the time.

Biden never faced a serious challenge in the Democratic primary, handily winning contests across the country in what amounted to a coronation. Phillips launched his campaign declaring “it’s time for a new generation,” but never rose above the nuisance level to the incumbent and his advisers. No Labels, a group that explored a potential bipartisan third-party ticket, failed to come up with a nominee, partly due to the country’s sharp polarization. The Democratic National Committee rescheduled the primary calendar to benefit Biden and declared there would be no primary debates.

As Biden ramped up his campaign, he sought to address his age by making light of it, telling one audience he was “a little under 103” and jokingly referring to “my good friend Jimmy Madison.” More seriously, his advisers pointed to special election wins for Democrats, saying they reflected the party’s strong position under Biden.

That mood of nervous acceptance blew up on Thursday.

During the debate, held in a CNN studio without an audience, Biden spoke in a raspy voice, struggled to parry Trump’s attacks, often rambled or appeared to lose his train of thought, and at times stared blankly while Trump spoke.

“Obviously that debate was a [f----ing] disaster,” Jon Favreau, a former Obama speechwriter and podcast host, wrote on X afterward, suggesting that Democrats needed to have a “serious discussion” about replacing Biden as their nominee.

“He seemed unprepared, lost, and not strong enough to parry effectively with Trump, who lies constantly,” wrote Julián Castro, the former Democratic mayor of San Antonio who served in Obama’s Cabinet.

Biden’s frequent admonition to skeptics to “watch me” suddenly seemed like a warning rather than a reassurance. Some Democrats privately questioned whether his choice to run one final race would ultimately be remembered as an act of selfishness rather than emblematic of a lifetime service.

Even those who accepted that Biden was unlikely to step aside argued that he needed a major strategy shift.

“The onus is on the folks who have a personal relationship with the president to have real conversations about how to improve his performance and really take stock of the moment,” said one Democratic official, who spoke on the condition of anonymity to speak bluntly about the president’s family members and close friends.

Incumbent president have traditionally struggled during their first debates, having grown unaccustomed to being challenged in such a sharp manner. But Biden’s performance was so “jarring” that it should prompt a fresh reassessment of his public appearances, said Joel Payne, a Democratic strategist who nonetheless supports the decision to seek another term.

Biden’s struggles Thursday were all the more unsettling to some Democrats because he had spent several days preparing for the debate. The group of advisers who helped Biden prepare at Camp David included many of the confidants who originally encouraged the president to seek another term.

Advisers to the president say the reaction to the debate has been wildly disproportionate.

Biden, they argue, has survived hard moments and has a track record of defying doubters. While they acknowledge that Biden’s performance was disappointing, they frame it as just one moment in what will be a long, tempestuous campaign.

In the first days after the debate, Democratic lawmakers have largely stuck by the president, dismissing suggestions that the party select a younger nominee. Donations have continued to stream in, with the Biden campaign declaring the hour after the debate its best fundraising moment so far.

Trump’s steady stream of falsehoods and bluster at the debate, meanwhile, may be prompting some Democrats to rally around Biden. The president’s campaign team met Friday to reassure staffers and recommit to the mission of defeating Trump in November.

Russell Riley, a presidential historian at the University of Virginia’s Miller Center, agreed that the debate’s significance will fade in weeks to come, saying, “A combination of time and the electorate’s short attention span mitigates damn near anything in presidential electoral politics.”

Ashley Parker and Tyler Pager contributed to this report.