Joe Biden began his press conference at the JW Marriott Hotel Hanoi in Vietnam at 9.09pm local time. “Good evening, everyone – it is evening, isn’t it?” he said, prompting laughter. About 25 minutes later, the 80-year-old US president had another quip: “I don’t know about you, but I’m going to go to bed.”

Headline writers pounced. The Daily Beast website declared: “Biden Wraps Up G20 Conference by Announcing ‘I’m Going to Bed’”. But unusually, the White House fired back. Ben LaBolt, its communications director, retorted sarcastically on X, the platform formerly known as Twitter: “Presidents shall never sleep. Not even at night after days of marathon meetings overseas. Sage guidance from the Daily Beast. Next up in the series: presidents shall never eat.”

The riposte, combined with sharp pushback from LaBolt’s colleagues, suggested a newly pugnacious approach from Biden’s communications team over that most delicate of subjects: his age.

A recent opinion poll by SSRS for the CNN network found declining shares of Democratic-aligned voters see Biden as inspiring confidence or having the stamina and sharpness to serve effectively as president. Asked to name their biggest concern about his candidacy in 2024, nearly half directly mentioned his age.

As a white man with a blue-collar background, Biden has effectively neutralised many familiar Republican attack lines on race, gender or class elitism. But the prospect of him being 86 at the end of a second term has provided fodder for critics. Nikki Haley, a former South Carolina governor running for the Republican presidential nomination, has called for mental competency tests for candidates over 75 and warned that Biden will almost certainly be replaced by Vice-President Kamala Harris before the end of a second term.

This week, David Ignatius, a venerable foreign affairs columnist for the Washington Post newspaper, lavished praise on Biden’s legislative achievements before contending that he and Harris should not run again. He wrote: “It’s painful to say that, given my admiration for much of what they have accomplished. But if he and Harris campaign together in 2024, I think Biden risks undoing his greatest achievement – which was stopping Trump.”

Biden’s age is a problem that poses a unique challenge for the White House and the president’s re-election campaign. Some have advised them to embrace it as evidence of his experience, knowledge and wisdom. Jeffrey Katzenberg, a film producer and media proprietor, remarked earlier this year: “President Biden’s age is, in fact, his superpower.”

But Frank Luntz, a consultant and pollster who has advised numerous Republican campaigns, described that as the “single dumbest political advice I have ever seen”. He explained: “Americans just say 80 is too old for being an effective president. The key is that Democrats are saying enough already, thank you for your service but don’t run for president, we need somebody else.”

Biden’s likely rival in next year’s election, former president Donald Trump, is just three years younger, but Luntz counsels Democrats against emphasising that point. “They can’t do that because Trump may be 77 but he acts seven.”

Biden’s Asia excursion illustrated the messaging opportunities and pitfalls around the issue. The White House points out that he “literally” travelled around the world – more than 18,000 miles – in under five days and met 20-plus foreign leaders. It gleefully quoted Peter Doocy, a reporter at the conservative Fox News network, who said from Hanoi: “He has basically been working all through the night. The equivalent of an all-nighter.”

But the climactic press conference was interpreted by some as feeding into an existing narrative seen in Franklin Foer’s recent book, The Last Politician, which reported that Biden holds strikingly few morning meetings or public events before 10am and occasionally admits feeling tired.

A report on CNN’s website said the White House press secretary, Karine Jean-Pierre, had “abruptly” ended the session and foregrounded Biden’s comment about “going to bed”. It did not go unanswered. Olivia Dalton, principal deputy press secretary, set out Biden’s very long day on X and demanded: “What will be enough?” LaBolt targeted the author of the article, adding: “The desk jockey who wrote this utter BS was not present at the press conference or the trip.”

It was an unusually personal, bare-knuckle approach from an administration that has condemned Trump’s frequent attacks on “fake news” and pledged to defend the freedom of the press.

Robyn Patterson, an assistant White House press secretary, defended the responses to negative coverage, saying via email: “At the conclusion of the trip, President Biden held a press conference in the standard format. The President was scheduled to take five questions – he ended up taking seven.

“He gave detailed answers on questions ranging from the US-China relationship, to his Indo Pacific strategy and climate change. When we see unfair spin that omits or downplays key facts and narratives ripped straight from right-wing Twitter, it’s our job to call that out.”

Political analysts contend that calling out individual members of the media is unlikely to win friends in the long term.

Kurt Bardella, a Democratic strategist, said: I don’t think it’s wise. When you make things personal like that it doesn’t serve any positive purpose. No journalist who gets called out is going to all of a sudden go, ‘Oh, you’re right, I see it your way now, let me bend to your will.’ If anything, it makes the White House look overly defensive and overly concerned and a little touchy.”

Reporters are not the problem but YouTube videos and TV coverage are, argues Charlie Sykes, editor of the Bulwark website and a former conservative radio host.

“It is out there. The question of Joe Biden’s age comes up in every single conversation with every voter in America and that’s not going to go away and you can’t just simply spin that by beating up on reporters. People are watching Joe Biden very carefully.”

The White House does need to rebut rightwing media claims that Biden is senile, Sykes added, because there is no evidence that he is unable to do the job. “But it seems naive to me to not recognise how the visuals undermine their message. The visuals of someone with a very stiff and wandering gait who sometimes loses the thread of conversation in these unstructured environments clearly is going to hurt them.

“What really haunts me is what if we’re having this conversation in September or October of 2024. What if there is a Mitch McConnell-like episode [the Senate minority leader has frozen twice at press conferences] with the president in the fall of 2024, especially when Joe Biden may be the only thing that stands between this country and the constitutional disaster of a second Trump term?”

Before Biden and Trump, the oldest American president was Ronald Reagan. When, at a debate in 1984, the moderator reminded him of this fact Reagan, then 73, replied: “I want you to know that also I will not make age an issue of this campaign. I am not going to exploit, for political purposes, my opponent’s youth and inexperience.” Even his Democratic opponent, Walter Mondale, laughed at the line. Reagan won re-election in a landslide.

Biden himself appears to have borrowed from the Reagan playbook, deploying self-deprecating humour and taking a less combative approach than his aides. He has joked about serving in the Senate 180 years ago and knowing “Jimmy” Madison, who was president in the early 19th century. At this year’s White House Correspondents’ Association dinner he made fun of his age several times.

Chris Whipple, a journalist and author of The Fight of His Life: Inside Joe Biden’s White House, believes this is a more fruitful way of handling the issue than going on the offensive. He said: “The answer is humour, not anger. It makes them look desperate when they get angry. The communications people in the White House should take a page from the boss and just try to keep a sense of humour.”

The challenges facing Biden, who turns 81 in November, were underlined this week when Republicans in the House of Representatives announced an impeachment inquiry into unproven allegations of corruption and his son, Hunter, was indicted on three criminal counts related to his alleged illegal possession of a gun.

His re-election effort will also include more travel and voter interaction than during the coronavirus pandemic lockdowns of 2020. Last week his campaign team released a video about his surprise visit to Ukraine, referencing that it was a near 40-hour journey that started at 4am and involved a nine-and-a-half-hour train journey to Kyiv. They can also point to Biden’s triumphant verbal sparring with Republicans at this year’s State of the Union address.

But there will have to be enough to drown out the many clips circulating on rightwing media of Biden falling off a bike near his Delaware beach house last year or tripping over a sandbag at the Air Force Academy commencement a few months ago. The president’s gaffes, a hallmark of his long political career, now tend to be seen through the prism of a fading octogenarian.

Elaine Kamarck, a senior fellow at the Brookings Institution thinktank in Washington and former White House official, noted that Biden had been making his case in speeches across the country and called for a sense of perspective. “His age will only be a liability if he’s running against somebody young,” she said. “It’s not going to be a liability running against Trump. You’ve just got to look at the guy.

“All that’s happened is so far the Republicans have been more aggressive on the age issue. But this is people throwing stones at glass houses. Trump is a walking heart attack, he looks a mess, he’s overweight and he talks in frequently incoherent babble. I don’t know if it’s dementia or just plain old stupidity. At least Joe Biden says things that make sense.”