If Donald Trump loses the White House to Joe Biden in November, one thought is liable to disturb his sleep ever after. No one has gone to such extreme and impeachable lengths to dig out the former vice-president’s ethical liabilities. And yet no one has done more to make them appear so banal. Had the US president not contributed so lavishly to the debasement of public life, Mr Biden’s fabulist tendencies might disturb more voters than they seem to. So might the vexed question of his son Hunter. As it is, neither kind of baggage is weighing down his surge in the Democratic primaries.

Mr Biden’s success shows us more than the higher bar for scandal since 1988, when a part-plagiarised speech and some puffed-up anecdotes were enough to end his presidential bid.

It also tells us to question the much-billed death of the political centre.