Joe Biden has twice made gaffes this week in which he told anecdotes wrongly identifying dead European leaders as having talked to him about the events of the attack on the Capitol on 6 January 2021.

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On Wednesday in New York, Biden reportedly referred to the former German chancellor Helmut Kohl as talking to him about European concerns about the attempt to stop the certification of his 2020 election win, when he apparently meant Angela Merkel. Kohl died in 2017.

Previously on Sunday, Biden in Nevada apparently confused François Mitterrand, the former French president who died in 1996, for France’s current president, Emmanuel Macron, while recounting a similar anecdote about the events of 6 January and European fears over them.

Biden, 81, is the oldest president to seek re-election in US history. Though physically fit and facing a demanding schedule, health concerns have become a persistent issue for many voters, including Democrats. A recent NBC News poll showed that three-quarters of voters, including half of Democrats, reported holding concerns about Biden’s mental and physical health.

Biden’s age has also been the subject of a concerted effort by Republicans and the rightwing media in the US to portray him as unfit for office, with every mistake pounced upon and highlighted. Biden has a career-long history of making verbal gaffes and has also struggled with a stutter.

Biden’s likely opponent in the 2024 race, former US president Donald Trump, is also known for making mistakes on the campaign trail.

Trump, who at 77 is similar in age to Biden, appeared recently to mix up his sole remaining serious opponent in the Republican nomination race, former South Carolina governor Nikki Haley, with ex-Democratic speaker of the House Nancy Pelosi. At a campaign rally in January, Trump said that Haley was in charge of security at the Capitol on 6 January 2021 as it was attacked.

Haley has criticized both Trump and Biden as being possibly too old for office, calling them “grumpy old men” in a campaign ad.