US President Donald Trump remains under scrutiny as he stays in hospital for Covid-19 treatment.
There is scepticism over the prospect – raised by doctors earlier – that he could leave on Monday as questions continue over the seriousness of his illness.
His oxygen level dipped twice and he received a steroid treatment.
On Sunday, he made a surprise public appearance in a drive-past to greet supporters, drawing criticism.
“More than 205,000 Americans are dead. We need leadership. Not photo ops,” tweeted Hakeem Jeffries, chairman of the Democrats in the US House of Representatives.
Wearing a mask, the president waved to well-wishers from behind the glass of a sealed car after tweeting that he would leave Walter Reed hospital to pay a “surprise visit” to “patriots” outside.
A doctor at the hospital strongly criticised the president’s motorcade ride due to the infection risk inside the car.
“That Presidential SUV is not only bulletproof, but hermetically sealed against chemical attack. The risk of Covid-19 transmission inside is as high as it gets outside of medical procedures,” Dr James Philips tweeted.
He said that those inside the president’s car would need to quarantine for 14 days and are at risk of getting ill.
Earlier, it emerged that the president’s condition was more serious than previously reported when he went to hospital Friday evening.
The White House had said that Mr Trump was experiencing “mild symptoms” of Covid-19, but it was confirmed at the weekend that he received supplemental oxygen after his levels dipped twice within two days.
He was given the steroid dexamethasone, which is normally reserved for serious cases, according to experts.
However, Mr Trump sought to project an image of strength, tweeting images of himself appearing to work from the hospital and a video message teasing his surprise drive past.