“There is an adage in politics,” says Heidi Heitkamp, a former Democratic senator from North Dakota. “When your opponent is shooting himself in the foot, don’t take his gun away.”

As the presidential election campaign begins in earnest, Donald Trump should have an inbuilt advantage. Social distancing rules mean that his Democratic rival Joe Biden has largely been confined to doing low-key events from the basement of his Delaware home.

Untroubled by such public health niceties, Mr Trump has begun a series of rallies designed to demonstrate the ironclad support of his base — while boosting the spirits of the president.