The 2020 election was always going to end like this.

Perhaps not precisely like this. Perhaps not with the president and the first lady contracting the coronavirus, along with the head of the Republican National Committee and members of the White House staff. Perhaps not with the campaign calendar thrown into disarray and the remaining debates in jeopardy…

As a singular force in the country’s political life, the pandemic has resisted Mr. Trump’s efforts to change the subject and quashed the wishful thinking of countless voters who shared his hope it would fade quickly. It has endured through a season of racial justice protests and spasms of vandalism and violence, through the death of a Supreme Court justice and the revelations of Mr. Trump’s personal tax returns and a fiasco of a presidential debate just this week.

And after all of the efforts by Mr. Trump to dismiss the disease as a threat, and all of the angst among his opponents that he might manage to convince voters he was right, his diagnosis confirmed with a neon exclamation point the impossibility of that goal.