2020 Election Live Updates: Biden Will Accept Nomination in Delaware, Skipping Milwaukee Convention

The reason the conversation resonated so deeply is simple: Mr. Trump was addressing the gravest responsibilities of his office, matters of life and death, on the cusp of an election. And it produced, arguably, his most memorable quote about a pandemic that has thus far killed about 160,000 people in the country.

“They are dying. That’s true. And you — it is what it is,” said Mr. Trump, moments after undercounting the number of dead Americans at 140,000.

Mr. Trump, the most unconventional of presidents, finds himself in the teeth of the most conventional of presidential dilemmas, trying to escape a slow-motion disaster he cannot control or talk out of existence.

That thought — control — was clearly on the mind of a president who has branded himself as a take-charge executive. “It’s under control, as much as you can control it,” he added.

In this respect, Mr. Trump is little different from President George W. Bush, whose popularity sank as the bloody Iraq war raged on, or the predecessor whose legacy he ridiculed in his interview with Mr. Swan — Lyndon Johnson, whose ambitious domestic agenda was undermined by the daily death toll from Vietnam.

Ask aides to Mr. Obama about the most frustrating point of his time in office, and many will point to the protracted 2011 oil spill in the Gulf of Mexico, a far less serious crisis over which they too had little control.

The 45th president has succeeded politically, in part, because he is so adept at speeding up a news cycle. A bad day, until now, could be erased with a bold, disruptive tweet or by floating an “unprecedented” idea (like hosting his nomination speech on taxpayer property, the South Lawn of the White House). One narrative interrupts the next, like the flipped pages of a forgotten beach novel.