Furthermore, he has no obvious challenger with the Democratic party and benefits from the same conditions as 2020: the fear that Trump poses an existential threat to democracy and the constitution and Biden is best placed to beat him.
Some 44% of Democratic voters say he is too old to run, according a Reuters/Ipsos poll, although it showed him with a lead of 43% to 38% over Trump nationally. Trump also faces concerns about his age, with 35% of Republicans saying he is too old.
A Biden v Trump rematch would also leave America facing its 250th birthday in 2026 with no female presidents and only one Black president in its history. It fares poorly by comparison with Australia, Britain, Finland, Germany, New Zealand and numerous nations that have elected women as leaders.
Trump could choose a female running mate, with potential candidates including Nikki Haley, a former US ambassador to the UN and one of his rivals for the Republican nomination. Biden will be joined in his 2024 bid by his vice-president, Kamala Harris, who features prominently in his campaign video.
But if Trump does prevail, Democrats insist that they can overcome voter fatigue.
