Donald Trump's chief of staff said Friday the president was experiencing "mild symptoms" of Covid-19, after the bombshell news of his infection upended the White House race a month before the Republican faces challenger Joe Biden at the polls.
The 74-year-old Trump -- who has continued to cast doubt on the seriousness of the pandemic, even as the US death toll topped 200,000 -- announced in an overnight tweet that he and First Lady Melania Trump, 50, had tested positive and were going into quarantine.
Briefing reporters at the White House Friday morning, Trump's chief of staff Mark Meadows said the president was experiencing "mild symptoms" but remained in "good spirits" and "very energetic."
"The American people can rest assured that we have a president that is not only on the job, will remain on the job, and I'm optimistic that he'll have a very quick and speedy recovery."
Meadows said Trump's doctor would continue to attend to him at the White House, declining to give details of any treatment being provided.
Melania Trump for her part tweeted that she was "overall feeling good" and hoping to recover fast.
"Thank you for the love you are sending our way," she wrote.
While its ultimate effect on the race remains unpredictable, the thunderbolt news had immediate electoral consequences for Trump, forcing him to cancel a rally planned later Friday in key swing state Florida.
Further ahead, it looked certain the Republican -- who is badly lagging the Democrat Biden in the polls ahead of November 3 -- would have to abandon a weekend trip to Wisconsin, another battleground, as well as a tour of western states next week.
And a question mark hangs over his second televised debate, set for October 15, against Biden -- who has made criticism of Trump's coronavirus response his key issue.
The Democrat, who was mocked by Trump for his conspicuous mask-wearing as they shared the debate stage -- unmasked -- last Tuesday in Cleveland, said he and his wife Jill wished the couple a "swift recovery."
"We will continue to pray for the health and safety of the president and his family," Biden wrote on Twitter.
News of Trump's infection right after one of his closest advisors, Hope Hicks, tested positive -- sparking fears of a cluster of cases emanating from the heart of the White House.
Trump met with dozens of people through the week and reportedly went to a fundraiser in New Jersey after it was known Hicks had contracted the virus.
The White House said it was carrying out contact tracing, while Melania Trump's spokeswoman said the couple's 14-year-old son Barron had tested negative.
Vice President Mike Pence, Treasury Secretary Steven Mnuchin and Secretary of State Mike Pompeo all let it be known they had tested negative, and the White House said Supreme Court nominee Amy Coney Barrett had also been given the all-clear.
But Republican Party chairwoman Ronna McDaniel, who was last with Trump on September 25, tested positive earlier this week, according to US media reports.
Trump's positive test was more than a PR disaster for a president who has staked everything on trying to persuade Americans that fears of the virus are overblown.
In what has become an overtly political gesture, Trump almost never wears a mask in public -- an example followed by his supporters and many of his aides.
The president has been using large rallies to try to change the subject from his much criticized Covid-19 response, vowing in a speech just Thursday that "the end of the pandemic is in sight."
All that is now on hold, and with the clock ticking on the election.
Now Trump has become the world's highest profile patient, proving that all the resources of the White House could not prevent the risk.
As the shock news sent global stocks sliding, leaders including Germany's Angela Merkel and Britain's Boris Johnson wished the president and first lady a speedy recovery -- while Russian President Vladimir Putin predicted Trump's "vitality, good spirits and optimism" would see him through.
Technically obese and in his 70s, Trump is in a higher-risk category.