It was supposed to be the moment he silenced his critics and quashed concerns over his fitness to take on Donald Trump this November.
The tight set-up had been carefully orchestrated by the US president’s top team, whose demands of having no live audience and microphones muted to stop Trump shouting over Mr Biden were duly met.
But Thursday night’s debate, potentially one of the most consequential moments of the election, was anything but a triumph for the Democrat leader.
The excruciating 90 minutes were punctuated by painful stumbles and pauses as Mr Biden struggled to string sentences together under the glare of the studio lights.
From the moment Mr Biden, 81, walked onto the Atlanta debate with a stiff gait and began waving to a non-existent audience, the hearts of scores of Democrat supporters sank.
In the early exchanges, Mr Biden coughed, sounded hoarse and repeatedly lost his train of thought. The first questions related to the economy, and Mr Biden paused to correct himself as he confused millions and billions and percentage figures.
Mr Trump, 78, turned to face him wearing the wide smirk of someone who knew their opponent was floundering.
In the debate’s most excruciating moment for the president, he became confused while discussing healthcare and tripped over his words before taking a protracted pause.
“We finally beat Medicare,” he began again before a moderator cut him off.
Mr Biden has proposed increasing taxes on people who earn more than $400,000 to boost spending on the welfare programme for over-65s.
His stumble was a gift for Trump, who accused Mr Biden on the night of seeking to destroy the security net for senior citizens.
“He did beat Medicare,” Trump chimed in. Beat it to death.”
Not long after, the White House began to brief out that the raspy Mr Biden was suffering from a cold.
Despite spending almost a week hunkered down with his top team at Camp David, Mr Biden’s secluded country residence in Maryland, he was unable to land effective blows in even some of the most promising areas for his campaign.
Ahead of the debate, Democrat strategists had highlighted abortion as a wedge issue that would tilt the election in their favour.
Mr Biden struggled to explain Roe v Wade, the historic 1973 Supreme Court ruling that legalised abortion nationwide.
When asked if he supported restrictions on abortion, Mr Biden rambled that he “supports Roe v. Wade, which had three trimesters. The first time is between a woman and a doctor”.
He added: “Second time is between a doctor and an extreme situation. A third time is between the doctor, I mean, between the women and the state”.
In an apparent non-sequitur, Mr Biden then mentioned a young woman who was recently murdered by an immigrant.
His bumbling responses distracted from Trump’s baseless allegations about doctors performing abortions and claims that some Democrats are willing to “kill babies” after birth.
While Trump pulled facial expressions when waiting for his turn to speak, Mr Biden looked down at his notes, expressionless as he prepared for his next answer.
Mr Biden delivered Trump another gift when he stumbled over his border policy proposals and trailed off by saying he would work to ban the “total initiative relative to what we’re going to do with more Border Patrol and more asylum officers”.
“I really don’t know what he said at the end of that sentence,” the former president jibed.
“I don’t think he knows what he said either.”
Trump made a string of false claims, suggested he would not accept the results of the election were he to lose in November and was forced to say: “I did not have sex with a porn star” when Mr Biden pressed him on his alleged affair with adult film actress Stormy Daniels.
One of the most farcical moments of the debate came when the two men began bickering about golf when asked about concerns over their ages.
Trump, who claims to have a handicap roughly half of that of a professional golfer, said Mr Biden had failed to answer his challenge to a round of golf and “can’t hit a ball 50 yards”.
Mr Biden fired back, telling him: “I’d be happy to have a driving contest. I got my handicap when I was vice president down to a six.
“By the way, I told you before, I’m happy to play golf with you if you carry your own bag. Think you can do it?”
“That’s the biggest lie – that he’s a six handicap – of all,” Trump answered,
“You are a child”, Mr Biden said back, injecting a rare moment of energy into the debate.
“I’ve seen your swing. I know your swing,” he said eventually, adding: “Let’s not act like children.”
“You are a child,” the president hit back angrily.
CNN host Dana Bash gave Mr Biden the chance to address concerns about his age, asking how he could reassure voters he would not be too old for office to serve another term that would leave him 86 years old.
The president appeared to be asking voters to judge him on his record, and began with a strong line on Trump, who he deemed “Three years younger, and a lot less competent”.
But then he pivoted away from any discussion of his glaring signs of age to a prolonged discussion of the microchip industry.
“I went to South Korea, I convinced Samsung to invest billions of dollars here in the United States,” he said.
“And guess what, those fabs they call – the Middle East chips – those fabs pay over $100,000, you don’t need a college degree for them,” he said, confusingly.
After the debate ended, Jill Biden, dressed in a powder blue suit, strode onto the debate stage from the wings to congratulate her husband. Trump left the stage, with no Melania Trump by his side.
Analysts said the rules had backfired on Mr Biden.
“If you think back to those terrible debates in 2020 where [Trump] was essentially trying to talk over Biden for the duration of Biden’s answers, that made Trump look horrible and I think made audiences more sympathetic with Biden”, Christopher Galdieri, professor of politics at Saint Anselm College said.
Mr Galdieri said he doesn’t think the Democrat-requested rules had “the effect that the Biden campaign expected when they requested them”.
He added that putting the two men next to one also made Mr Biden look “noticeably older than he was four years ago.”
“Trump looks like Trump”, he said, adding that Mr Biden looks “thinner, he’s frailer, he’s slower, and all these things sort of add up to a visual picture that I think reinforced a lot of concerns that voters would express.”
When Mr Biden challenged Trump to an election debate earlier this year, he had urged him to “make my day, pal”.
In the end, one man’s day was certainly made – and it wasn’t Mr Biden’s.
