The American Left is looking increasingly extreme: How will Joe Biden's radicalised supporters react to a Trump victory in November?

There has been much chatter about what Donald Trump might do if he were to lose in November. Or, more to the point, what might he do if he wins — or seems to be winning — on the night of the election only to lose when postal votes are counted over the days (or weeks) afterwards? Who knows what his supporters might be capable of?

But there is another question, asked less often but certainly looming in the background this autumn. What would the Democrats and their supporters do if they lost?

Not Joe Biden — we know he’d go quietly. But what about the anti-Trump protesters on the streets of Portland, Oregon, of Seattle, of Chicago, of Washington DC itself. The bandana wearers. The stone throwers. The corner store looters.

Donald Trump’s disinclination to accept defeat is rather well known, but his opponents on the Left are assumed to be hewn from more democratic timber. For all the complaints about Russian interference and other criminality, they sucked it up in 2016.Would they, again?

It has to be an open question. It may become — if Trump hauls himself out of the electoral mess he is in — a central question, on which the future of America hinges, and polling does not lead to optimism: already 28% of Biden supporters say they will not accept a Trump victory as fair and accurate, compared to 19% of Trump voters.

The forces of the American Left are not controlled by shadowy figures in dark clothes, but they are organised and angry in a way that they have not been in recent history. So what do they believe is acceptable in the effort to resist Donald Trump, and how far will they go?