The Wall Street Journal became the latest major publisher to highlight the president’s age over the weekend.
“Given Mr Biden’s age and obvious decline, running for re-election is an act of profound selfishness,” the newspaper’s editorial board wrote.
Noting that his campaigning will be scaled back, it added: “Why would voters think he can handle four more years of a gruelling job, which might include being shaken awake in the wee hours to respond to a Chinese invasion of Taiwan?”
Andrew Bates, a White House spokesman, said that Mr Biden “has used his deep experience to deliver unprecedented benefits”.
While the US president is convinced he has enough in the tank to carry on in the Oval Office into his 86th year, polls show the view is not shared by American voters.
They indicate his mental and physical fitness are a pressing concern not just for Republican voters, but Democrats too.
In a Yahoo News/YouGov poll last week 54 per cent of respondents thought Mr Biden no longer had “the competence to carry out the job of president” – an increase of five per cent since February.
But behind the scenes the Biden camp is being urged to challenge the public fear over his age.
Make a virtue of his age
Politico said it spoke to dozens of concerned party officials and donors.
John Morgan, a Biden fundraiser and Florida attorney, said he had urged the president’s team to make a virtue of his age.
“You cannot roll back time. There’s nothing that can be done to make him younger,” Mr Morgan said. “I believe that what’s going to carry the day for Joe Biden is the word “wisdom”. We want wise men.
“And to everybody who has a problem with his age, I would tell them that if you had stopped investing with Warren Buffett when he was 80, you would have missed out on 12 years of record returns.”
Mr Bates said that Mr Biden “has used his deep experience to deliver unprecedented benefits”.
The president and first lady Jill Biden were on Sunday night due to join military personnel and their families for an early Thanksgiving meal dubbed “Friendsgiving”.
He conducts the traditional pardoning of the Thanksgiving turkey on Monday, and then leaves on Tuesday for the Atlantic island of Nantucket to spend the Thursday holiday there with his family.
Cue cards to minimise gaffes
Glossing over Mr Biden’s birthday is the latest attempt by the White House to control the narrative for the gaffe-prone president.
Part of this involves his team carefully managing his schedule, with most of his public appearances occurring between midday and 4pm, according to an analysis by US media.
On gruelling overseas trips he has occasionally skipped dinner rather than using the comparative informality of the occasion to engage in soft diplomacy with other world leaders.
He is given cue cards to minimise the chances of embarrassing verbal gaffes.
And even his ascent and descent from Air Force One has been tweaked with shorter stairs.
Frank Luntz, an American pollster who has known Mr Biden for years, predicts the White House will deploy “the rose garden strategy” for the 2024 campaign, essentially maximising the power of the Oval Office to get media coverage rather than “travelling the country”.
Mr Biden has tried to defuse the issue by making self-deprecating jokes about his age. However, the effectiveness of this strategy is a matter of debate.
Minnesota Democrat congressman Dean Phillips has stuck his head above the parapet, challenging Mr Biden for the nomination and saying it is time for the president to pass the torch.