President Donald Trump has not self-isolated despite meeting at least one person who has the coronavirus.
Fabio Wajngarten, an aide to the Brazilian president, was confirmed with the disease after a Mar-a-Lago visit.
"No, we have no symptoms whatsoever," Mr Trump told reporters on Friday when asked why he has not been tested or why he has not self-isolated.
After a barrage of further questions at a White House news conference, the president said he would get tested.
Official US advice is that people who have contact with a confirmed case should stay at home for 14 days.
Mr Wajngarten has posted a photograph of himself standing shoulder to shoulder with Mr Trump.
When asked if individuals should be tested after standing next to someone with the virus, said Dr Anthony Fauci, who is leading the US response, said yes.
There are nearly 2,000 confirmed cases of Covid-19 in the US, and 43 deaths.
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Several US states have taken measures to stem transmission rates including banning large gatherings, sporting events and closing schools.
On Friday, Mr Trump declared a national state of emergency to release $40bn to fight the spread of the virus.
What is the risk to President Trump?
Mr Wajngarten, a press secretary for Brazilian President Jair Bolsonaro, met Mr Trump and Vice-President Mike Pence on a recent visit to the president's Florida resort, Mar-a-Lago.
Days later he tested positive.
Miami Mayor Francis Suarez - who also met Mr Wajngarten during his US trip - announced on Friday that he had tested positive for the virus.
The Brazilian delegation also met Mr Trump's daughter Ivanka Trump, his son-in-law Jared Kushner and his personal lawyer Rudy Giuliani.
Republican Senator Lindsey Graham, also present at Mar-a-Lago, announced on Thursday that he would self-quarantine "in an abundance of caution", joining a growing number of lawmakers to do so.
Any other potential exposure?
The president attended the Conservative Political Action Conference (CPAC) in Washington, DC last month, where someone who later tested positive mingled with several conservative lawmakers.
Several Republican members of Congress - including Florida congressman Matt Gaetz, Georgia congressman Doug Collins, Arizona congressman Paul Gosar and Texas Senator Ted Cruz - all announced they would self-quarantine as a precautionary measure after coming into contact with the infected person.
Mr Collins and Mr Gaetz - who has since tested negative - came into close contact with Mr Trump shortly after the conference.
What has the White House said?
The White House has continuously played down the president's exposure to the virus and has dismissed the need for him to be tested or to self-isolate.
Asked if Mr Trump would follow the lead taken by his fellow Republicans after the confirmed case at CPAC his spokeswoman said there was "no" concern about the president's exposure.
Mr Trump "had almost no interactions with the individual who tested positive and do not require being tested," said spokeswoman Stephanie Grisham.
"There is currently no indication to test patients without symptoms, and only people with prolonged close exposure to confirmed positive cases should self-quarantine."
What did Justin Trudeau do?
This week, Canadian Prime Minister Justin Trudeau announced he would enter 14-day self-quarantine after his wife, Sophie Grégoire Trudeau, tested positive for the virus.
There are no plans for Mr Trudeau to be tested.
Speaking to press on Friday, the prime minister said he was taking advice from doctors and "it was explained to me that as long as I show no symptoms at all there is no value in being tested".