Are America’s leading presidential candidates Joe Biden and Donald Trump up to it?

“I really hate doing this, but I cannot not do it,” announced the conservative host Hugh Hewitt on his online show.

This was a preface to a montage of video clips showing “President Biden’s obvious and increasing infirmity”.

One, from a star-studded fund-raiser held in Los Angeles on June 15th, shows Mr Biden staring blankly at the audience before Barack Obama, the night’s other headline act, grasps his arm and leads him offstage.

The second, taken a few days earlier at the g7 summit in Italy, appears to show Mr Biden wandering away from other world leaders as they watch a skydiving demonstration.

In conservative corners of the media and the internet, such clips of Biden freezes abound. Another recent entry shows the president staring blankly at a White House concert celebrating the new federal holiday of Juneteenth on June 19th, which marks the end of slavery.

Selective editing of the clips makes them look more devastating than they are.

A longer recording of the Los Angeles episode shows Mr Biden waving to one side of the audience and clapping before turning and standing still for about seven seconds—possibly to try to hear what was being shouted (Mr Obama intervened before anything more awkward could occur).

A fuller clip of the Italian incident shows that Mr Biden did not wander off into the distance but rather to greet a skydiver who had landed off-screen (though Giorgia Meloni, the Italian prime minister, similarly intervened to bring him to centre stage).

This is not to say that the president is a paragon of lucidity. Mr Biden, an octogenarian, certainly has his senior moments. Some are hard to explain away: in 2022 he wondered whether a recently deceased congresswoman was in a crowd at a White House event (“Where’s Jackie?” he asked to silent horror).

The special counsel appointed to investigate classified documents at Mr Biden’s house said that he frequently confused dates, including of his son’s death in 2015. The transcript of the interview is not exactly exonerating.

The fracas gives a preview of what the next five months of campaigning will look like.

Donald Trump and his allies will relentlessly scrutinise the president’s public appearances for signs of senility and distribute clips purportedly showing this (there is little need for ai-generated disinformation when simple editing tools do so well). Mr Biden’s campaign will be anxious not to give them too much material to work with, reinforcing a bunker mentality.

Allies of Mr Biden wonder why more is not made of Mr Trump’s strange utterances.

On June 9th at a rally in Las Vegas, the former president told a bizarre, lengthy hypothetical story about being electrocuted by a battery-powered boat while being chased by sharks.

It might be an enjoyable, absurdist scene in a b-horror film, were it not for the scarier fact that the raconteur is the leading contender to win the presidential election.

Mr Trump, who is 78, has also confused the leader of Hungary for that of Turkey and mistakenly said that Mr Obama was now president.

Democrats are right about the difference in standards. Such utterances are barely news stories for Mr Trump; Democrats might forcibly commit Mr Biden to an elder-care facility for a monologue like that.

Yet the difference in standards is the point. Mr Biden’s pitch is competent, rational leadership, whereas Mr Trump has been a surrealist from the start.

Voters appear to be steeling themselves for a dismal choice.

A recent poll conducted for CBS News by YouGov found that just 35 per cent of registered voters say Mr Biden is mentally and cognitively healthy enough to be president; even 29 per cent of registered Democrats say they are not sure their man is all there.

The same poll found that 50 per cent of voters thought Mr Trump was mentally fit for office. Only in this contest could such a result be thought of as positive.

Mr Trump is sure that he has the cognitive advantage. His campaign has pushed for holding multiple debates, on the theory that Mr Biden would not be able to keep up either rhetorically or physically.

While president, Mr Trump memorably bragged about his high marks on a mental-acuity test (meant as a diagnostic tool for early dementia, not admission to MENSA).

Speaking in Detroit this week, Mr Trump challenged Mr Biden to take the same test he had “aced”.

While issuing the blustery challenge, Mr Trump got confused about the name of the White House physician who administered it to him: he was Ronny Jackson, not “Ronny Johnson”.