U.S. President Donald Trump will remain in hospital for a “period of time,” a key White House official said on Sunday.

The official ruled out the need to move towards a transfer of power within the federal government.

National Security Adviser Robert O’Brien told broadcaster CBS that day seven and eight after the onset of symptoms are the “critical days” for any patient.

Mr. Trump was diagnosed on Thursday with the new coronavirus and was moved, the next day, to the Walter Reed medical centre, a military facility outside Washington.

He apparently had some breathing difficulties initially, but his doctors say his condition has improved and that the medical team “remains cautiously optimistic’’.

His oxygen levels were back within a normal range on Saturday.

The president received an antibody cocktail and is on a treatment course of Remdesivir.

Mr. Trump issued a four-minute video on Saturday from the hospital.

Wearing a blue suit jacket and no tie, the president insisted he was “starting to feel good’’ and would soon be back to work at the White House.

The illness has thrown Trump’s re-election campaign into a tailspin, with just 30 days to go until the November vote.

The team has been trying to put forward a sense of normalcy but campaign manager, Bill Stepien, is among a number of people in Trump’s inner circle to have contracted the coronavirus in the past week.

Jason Miller, a campaign adviser, was pressed on ABC’s This Week about the president often refusing to wear a mask and holding large rallies, insisting that Trump has taken the virus “very seriously”.

He attacked Democratic presidential nominee, Joe Biden, for using masks as a “prop”. 

(dpa/NAN)