Midway through the news conference that many American political commentators had built up as critical to Joe Biden’s re-election chances, the US president said European leaders are not asking him not to run for a second term, “they’re saying you gotta win”.

The problem for Biden and his advisors is that many American voters – regardless of this press conference or that debate – are concerned that to ensure the latter, Biden has to accept the former. That ‘you gotta win’ is in fact code for ‘you gotta stand aside’ because Americans are losing faith in his ability to serve as president for another four years.

The Friday press conference (NZT) lasted nearly an hour and Biden spoke strongly. His grasp of history, details of his recent meetings, economic figures, casualty numbers and more were impressive, especially in contrast to the CNN debate two weeks ago, which he today called his “stupid mistake”. Foreign policy has always been his strong suit.

But there were still slips. He spoke about “Vice-President Trump” when talking about Kamala Harris, without recognising his error. He said he was getting advice from his Commander-in-Chief before correcting himself, saying he meant his Joint Chiefs of Staff.

Biden though was dismissive of public concerns, declaring he’d only stand aside if people could convince him he had “no chance of winning”.  (Which is a step down from last week when it was only the Lord Almighty who could convince him). In this press conference he said the only question that matters is “Am I getting the job done?”. He quite reasonably pointed to a successful NATO summit and new economic figures showing overall prices coming down for the first time in four years as signs he’s doing the business. This press conference affirmed that this is a man who wants to stand on his record and his ability to build consensus. He said he had decided to stand for a second term because he’s not only the best qualified to govern, he’s the best qualified to win. And nothing had changed his mind about that.

Biden’s problem is that while his mind may be set, voters’ minds are in flux. This press conference or the next one won’t make them forget his incoherent debate night. Biden’s capability as an 81 year-old – and an 84 year-old before the end of a second term – has been simmering as an issue with voters for some years, but now the cat is out of the bag and is the dominant issues of the nascent campaign. Voters are now primed to watch for every memory lapse or slip and even as new issues arise, his mental agility and ability to lead will put the Democrats’ chance of winning in jeopardy.

The night before this press conference a Washington Post-ABC News-Ipsos poll showed Biden and Trump neck and neck in the popular vote, both on 46 percent. But 67 percent of those polled and even 56 percent of Democrats polled said he should “step aside and let someone else run”. Many voters are desperate for a candidate - any candidate - who can string a sentence together and isn’t breaking record as the oldest presidential candidates of all time. More Democratic politicians are expected to call for him to let someone else run now that the NATO summit is done.

As much as some are talking about a unique moment in history, US politics always rhymes with the past. There has been another time, for example, when the Democrats had a president approaching a convention and nomination in a perilous state of health. People around him noticing his flagging energy and lapses in concentration. Questions about what the public have been told and a vice-president’s capabilities. A war and serious global threats hanging over it all.

In 1944 Franklin D. Roosevelt – who had battled polio for more than 20 years – was suffering with heart issues, bronchitis, and exhaustion but still accepted the Democrat’s nomination for an unprecedented fourth term, ran and won in November.

He did what he could to fight his condition and hide his ailments, but died in April 1945, early in the new term. It’s a sobering thought. And Biden cannot hide his issues in the way Roosevelt (or Kennedy or Lincoln) did. Even though he has done roughly half as many press conferences as Barack Obama at the same stage of his first term and is carefully managing his public appearances, he can’t hide the toll age his taking on him any more than he can control the memes on Instagram or flood of images on X.

Yet this is not a campaign the Democrats can afford to be about Biden’s age. Or one they can afford to risk out of deference for Biden’s status in the party. For all the difficulties of recent years, it’s worth saying out loud that the Democrats should hose this election. The economy is recovering, as data is starting to show; they have a push-button issue in abortion to get out women and independent voters; and the Republicans are about to nominate a candidate who has not only lost the last three elections he has stood in or tried to influence, he’s a convicted felon. The Dems should win comfortably.

Biden himself has warned the world of a potential Trump dictatorship as Trump has toyed with that word in speeches. Biden has said Trump embraces political violence and another Trump presidency would imperil many US political institutions. “We can’t let that happen," he has previously said.

The concern for the Democrats and those around the world who fear what a second Trump presidency would mean for US and global democracy, is that they agree with Biden’s words that Trump must be beaten at all costs, but less with his words that he is best qualified to do it. Biden’s mental capacity is now on the ballot, so the question becomes political. It’s no longer whether Biden is doing the job, it’s whether Democrats think enough voters will hold their nose and tick Biden anyway or whether a new name on the ballot is needed to win. And with the party’s nomination due to be decided on August 5, they only have a few weeks to decide.