“The campaign as we knew it is over,” said Andrew Feldman, a Democratic strategist in Washington. “This is the worst nightmare for the Trump campaign.”

Practically speaking, Trump’s announcement early Friday that he tested positive for the coronavirus will immediately remove him from in-person campaigning, though for how long is unclear. Sean Conley, Trump’s physician, said in a memo that Trump and First Lady Melania Trump, who also tested positive, “plan to remain at home within the White House during their convalescence,” and the White House removed a planned campaign rally on Friday night in Florida from Trump’s daily schedule.

Trump’s inability to hold rallies, even for a brief period, will hobble a campaign that has defined itself by its large, in-person gatherings, even during the pandemic. The second presidential debate, now scheduled for Oct. 15, is in doubt. And Trump’s positive test will heighten scrutiny of the vice presidential debate scheduled for next week.

But the more significant problem for Trump is that, now Covid-positive, it will prove almost impossible for him to steer public attention away from his biggest political liability.