[homoe]

WASHINGTON — When Senator Bernie Sanders lost the Democratic nomination and the economy collapsed this spring, two pillars of President Trump’s re-election strategy collapsed at the same time: his plan to run on prosperity and against a far-left opponent. But Mr. Trump’s campaign took comfort in the expectation that Joseph R. Biden Jr.’s penchant for gaffes would at least offer them dependable fodder for attack.

The pandemic, and Mr. Biden’s play-it-safe campaign, however, have starved them of even that.

With mandated social distancing measures entering their fourth month in many states, Mr. Biden has held few events and therefore committed few missteps. He conducts television interviews and has slowly started to hold public events. But Mr. Biden’s aides said they had no plans to stage the sort of rallies Mr. Trump will begin holding again Saturday — and which the president’s campaign had been counting on as the most reliable source of Biden gaffes.

So Mr. Trump’s advisers are trying to flush Mr. Biden into the open. They have taken to taunting him for remaining in the basement of his Delaware home, and counting the days since he last held a news conference. On Thursday they demanded that the former vice president agree to more debates in the fall, asking for four instead of the traditional three.