Donald Trump’s 2016 victory caught most people by surprise, including him. The safest position since then has been to assume he will do it again. But there is a point at which once-bitten-twice-shy becomes intellectual abdication.

Most of the numbers, including the Trump campaign’s polls, show him heading for defeat in November. Common sense points the same way. It was one thing for Mr Trump to defeat Hillary Clinton — then America’s most polarising figure. It would be another for him to beat the generally liked Joe Biden, the president having long since surpassed Mrs Clinton’s divisiveness.

Mr Trump’s worsening odds can be gauged by his rising sense of panic. The simplest metric are his tweets, which now average four times as many per day as his first year in office, and almost three times as many as in his second year. Twice this year, including on Mother’s Day, Mr Trump tweeted more than 100 times when most of America was asleep.