President Donald Trump has tested positive for Covid-19, upending the already chaotic US election, but was described by his doctor on Friday as feeling "well" and able to perform his duties while quarantining.
Trump first announced on Twitter that he and First Lady Melania Trump had tested positive for the virus.
But the extraordinary setback for Trump had immediate political consequences just 32 days before election day.
His challenger, Democrat Joe Biden, is well ahead in the polls and is making criticism of the Republican's handling of the coronavirus pandemic a key plank in his campaign.
Trump, in response, has been betting on an evermore aggressive schedule of campaign rallies around the country -- bringing together thousands of people, often without masks.
Early Friday the White House canceled his planned campaign rally in the crucial swing state of Florida later in the day.
It also looked certain that Trump would have to cancel a trip scheduled for this weekend in Wisconsin, another battleground. He had also been expected to travel frequently next week, including longer distances to western states.
Trump's official physician, Sean Conley, said in a statement that the president and his wife "are both well at this time and they plan to remain home at the White House during their convalescence."
Conley said: "I expect the president to continue carrying out his duties without disruption while recovering."
The shock news came right after one of Trump's closest advisors, Hope Hicks, was reported Thursday to have come down with the virus.
Hicks traveled with Trump to Cleveland for his first debate with Biden on Tuesday. She was with him again for a campaign rally in Minnesota on Wednesday.
With Hicks sharing Trump's Air Force One plane and the even more cramped confines of the Marine One helicopter, speculation immediately erupted that Trump and possibly many others in his close entourage were exposed.
Despite Hicks' diagnosis, Trump took another Air Force One trip on Thursday to meet with donors in New Jersey.
It was only late Thursday that Trump confirmed media reports about Hicks while giving an interview to Fox News. He announced that he had been tested but did not say whether he had received the results.
"You know I spend a lot of time with Hope, and so does the first lady," Trump said.
Trump says the United States has put behind the worst of the coronavirus pandemic, which has killed more than 200,000 Americans, and he rarely wears a mask, noting that he receives frequent testing.
However, his own health experts have often given less rosy assessments of the state of the pandemic in the world's richest country.
And Trump has been sharply criticised for the large rallies where few supporters wear masks. He himself has given mixed signals to the public on the need for wearing masks at all.
By contrast, Biden has run a low key campaign with social distancing at most events, no large gatherings, and conspicuous use of his mask wherever he goes.
White House spokesman Judd Deere earlier said "the president takes the health and safety of himself and everyone who works in support of him and the American people very seriously."
Deere said the White House takes care to follow procedures "for limiting Covid-19 exposure to the greatest extent possible both on complex and when the president is traveling."
