Even when discharged, he has yet to finish a five-day course of an intravenous antiviral drug, remdesivir, by Tuesday, according to Brian Garibaldi, a member of Trump's medical team and a lung specialist.

Doctors also have been treating the president with a steroid, dexmethasone, normally used only in the most severe cases, and a dose of an experimental antibody cocktail being developed by US drugmaker Regeneron, according to his medical team.

Conley said doctors were in "a bit of uncharted territory" because Trump had received certain therapies so early in the course of the illness.

"If we can get through to Monday with him remaining the same or improving, better yet, then we will all take that final, deep sigh of relief," he said.

The doctor continued to be evasive to questions about when Trump last tested negative, or if the disease could take any potential toll on the president's lungs.

About 65 percent of Americans said Trump would not have been infected had he taken the virus more seriously, according to a Reuters/Ipsos poll released Sunday.

Nancy Pelosi, speaker of the House of Representatives, said earlier in the day that she hoped people could hear "trustworthy report" from Trump's doctors about his release from the hospital, and she was concerned that his returning to the White House was for political reasons.

"He should not be dealing with it politically to make it look like he overcame the virus because he had such good policies, because in fact he has been very destructive and dangerous to the country," the Democrat told MSNBC.

White House press secretary Kayleigh McEnany said on Monday she had tested positive for the virus and was going into isolation.

More than a dozen other people who had been in contact with the president or attended White House or campaign events last week also said they had tested positive. They include aide Hope Hicks, Trump campaign manager Bill Stepien, former adviser Kellyanne Conway and former New Jersey governor Chris Christie, who helped Trump prepare for last week's debate.

"We have to be realistic in this: COVID is a complete threat to the American population," The Associated Press quoted Dr David Nace of the University of Pittsburgh Medical Center, an expert on infections in older adults, as saying.

"Most of the people aren't so lucky as the president," with an in-house medical unit and access to experimental treatments, Nace added.