Donald Trump’s physician says the US President has completed his course of therapy for the coronavirus and could return to public engagements as early as Saturday.

The all clear comes amid a push by Democratic politicians for Mr Trump to prove he is fit to serve as president.

In a memo released by the White House on Friday (Australian time), Dr Sean Conley said Mr Trump had responded “extremely well” to treatment without any evidence of adverse effects.

House Speaker Nancy Pelosi earlier announced legislation that would allow the US Congress to intervene and remove the president from executive duties.

Ms Pelosi, a veteran Democrat, noted Mr Trump’s odd public appearances since leaving hospital and his “strange tweet” halting talks on a new coronavirus aid package.

She said Mr Trump needed to disclose more about his health after his COVID-19 diagnosis, including when he first contracted the virus as others in the White House became infected.

“The public needs to know the health condition of the President,” Ms Pelosi said, later invoking the 25th Amendment to the US Constitution which allows a president’s cabinet or Congress to intervene when a president is unable to conduct the duties of the office.

The President wasted no time in responding on Twitter, saying: “Crazy Nancy is the one who should be under observation. They don’t call her Crazy for nothing!”

Mr Trump was taken to hospital on Friday after he announced he had contracted the coronavirus. He returned to the White House on Monday.

“Since returning home, his physical exam has remained stable and devoid of any indications to suggest progression of illness,” Dr Conley wrote.

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— Jackson Gosnell (@jacksongosnell) October 8, 2020

“Saturday will be day 10 since Thursday’s diagnosis, and based on the trajectory of advanced diagnostics the team has been conducting, I fully anticipate the President’s safe return to public engagements at that time.”

Mr Trump, who has been confined to the White House with the illness that he has sought to play down, said earlier he did not believe he was contagious and was feeling good enough to resume campaign rallies.

Such rallies, particularly held indoors, have raised concern among public health experts about spreading the virus.

“I’d love to do a rally tonight. I wanted to do one last night,” Mr Trump said.

He added: “If I’m at a rally, I stand by myself very far away from everybody.”

On Thursday (Australian time), Mr Trump released a video claiming he felt great, and that catching the virus was a “blessing from God”.

“Perhaps you recognise me, it’s your favourite President,” Mr Trump said before praising America’s doctors and nurses.

He also used the video – shot in a garden at the White House – to claim the experimental antibody cocktail produced by biotech company Regeneron that he was treated with – and which has rarely been administered outside clinical trials – was a “cure” for coronavirus.

“It was, like, unbelievable. I felt good immediately,” he said.

Mr Trump’s clearance to return to campaigning, with just weeks to go until the November 3 election, came as he said he would not take part in a second debate with rival Joe Biden.

The pair were set to square off in a town hall-style second debate in about a week but organisers unilaterally decided it would happen virtually due to the President’s COVID diagnosis.

“I’m not gonna waste my time on a virtual debate, that’s not what debating is all about,” Mr Trump told Fox Business News.

“You sit behind a computer and do it, debates? Ridiculous. And then they cut you off whenever they want.”

There are also reports that the growing coronavirus outbreak linked to the White House is worrying some Republicans.

At an event in northern Kentucky this week, Senate Majority Leader Mitch McConnell – a staunch Trump ally – said he had not visited the White House in more than two months because of how it has dealt with the pandemic.

“My impression was their approach to how to handle this was different than mine and what I insisted that we do in the Senate, which is to wear a mask and practice social distancing,” the 78-year-old Republican and polio survivor said.

Several Trump aides and White House staff members have been infected in the outbreak, as well as the first lady, Melania Trump.

-with AAP