Top US virus expert Dr Anthony Fauci has criticised the White House for hosting a gathering last month that has been linked to an outbreak of Covid-19, reports BBC.
Dr Fauci, a member of the White House's coronavirus task force, said the president's unveiling of his judicial nominee was a "superspreader event".
Dozens of White House aides and other contacts were reportedly infected.
President Donald Trump's doctors have just cleared him to hold public events as he himself recovers from Covid-19.
Mr Trump - who was discharged from hospital on Monday after three nights - held a medical "evaluation" on Fox News on Friday night.
He is expected to host an in-person White House event on Saturday.
What did Dr Fauci say?
CBS News asked on Friday what Dr Fauci thought of the White House's reluctance to insist on mask-wearing and social distancing as virus precautions, and instead rely on regular testing.
"The data speak for themselves - we had a superspreader event in the White House, and it was in a situation where people were crowded together and were not wearing masks."
Dr Fauci also noted experts have been recommending mask-wearing for the last six months, and condemned talk of a coronavirus "cure" - a word Mr Trump has used in reference to the experimental Covid-19 treatments he received during his recent stay at a military hospital.
An event at the White House on Saturday 26 September, for the president's nomination of Amy Coney Barrett as a Supreme Court judge, is thought to be the root of the localised outbreak, as many attendees have since tested positive.
Large gatherings are still banned in the nation's capital due to Covid-19, but federal property like the White House is exempt.
What events does Mr Trump have planned?
On Saturday, which according to his doctors will be 10 days since his diagnosis, Mr Trump will give a speech from the White House balcony to a group gathered on the South Lawn.
Hundreds of people have reportedly been invited.
All attendees will be required to wear masks, will be given temperature checks and encouraged to social distance, said the White House.
Mr Trump's remarks will be on the subject of "law and order", according to the White House, which adds that it is a presidential rather than a campaign event.
There will also be an event by the group Blexit, a campaign urging black voters to reject the Democratic party.
On Monday the Trump campaign is planning a big rally in Sanford, Florida.
What about the debates?
Next week's second presidential debate between Mr Trump and his Democratic White House challenger Joe Biden is now officially cancelled.
The Commission on Presidential Debates said in a statement on Friday that both campaigns had announced "alternate plans for that date".
Mr Trump had baulked at a request from the commission that the 15 October showdown be held virtually to minimise the risk of spreading coronavirus.
The commission said it was still making arrangements for the third and final presidential debate in Nashville, Tennessee, on 22 October.
Who has tested positive in Mr Trump's circle?
The announcement of Mr Trump's first mass gathering since his infection triggered alarms in Washington, where officials are still attempting to contact trace attendees from the White House event that infected several Republican senators, Mr Trump and his wife, and several other high level White House aides.
Mr Trump tested positive for Covid-19 last Thursday, according to his doctors, but he has not said when his last negative test was.
As many as 34 White House aides and other contacts have tested positive for Covid-19 in recent days, according to US media.
On Friday, the Minnesota Department of Health said nine infections have been tied to Mr Trump's 18 September campaign rally in the state.
At least one person was infectious when they attended, officials say, and two cases have led to hospital admissions with one of those people in intensive care.