Just after the 2016 election of US President Donald Trump, a Harvard professor remarked to me: “I think the US can survive four years of Trump. Eight years and we’ll really be in trouble.”

Now with the emergence of Joe Biden as the probable Democratic candidate to run against Mr Trump in November — and the political and economic confusion caused by coronavirus — the Democrats are daring to hope that Mr Trump will indeed be gone by January. If that were to happen, many would echo Gerald Ford, who announced after the Watergate scandal, “Our long national nightmare is over”.

Many Europeans, hoping for a revival of the western alliance, share the hope that the Trump presidency might soon be dismissed as a weird aberration — and that an administration led by the former vice-president would effectively reset the geopolitical calendar to January 20 2017, the day Barack Obama left office. It is a nice idea. And it is one that Mr Biden, with his references to “my buddy, Barack”, has encouraged. But it is also an illusion.