Joe Biden has tested positive for Covid-19 and is suffering mild symptoms, the White House has said.
Karine Jean-Pierre, his press secretary, said the US president is vaccinated and boosted. He has tested positive for Covid twice before.
Mr Biden, 81, was seen earlier on Wednesday visiting supporters in Las Vegas and speaking at an event. He has cancelled a campaign speech later in the night.
The illness comes as he faces increasing pressure to step aside because of his age.
US media reports both Senate Majority Leader Chuck Schumer and House Majority Leader Hakeem Jefferies - the top two Democrats in the US Congress - separately met with Mr Biden privately and expressed that there is deep concern his candidacy could negatively impact other House and Senate races.
Ms Jean-Pierre said the president planned to isolate at his home in Delaware while he carries out "all of his duties fully during that time".
The president's doctor, Kevin O'Connor, said Mr Biden presented with upper respiratory symptoms, including a runny nose and a cough and was given his first dose of Paxlovid.
Credit: BBC