Corey Lewandowski, a senior advisor to President Donald Trump's campaign who has been involved in the legal efforts to challenge the election results, has tested positive for coronavirus, US media reported on Thursday.
Lewandowski, 47, is the latest member of Trump's inner circle to contract Covid-19.
The New York Times said Lewandowski is one of at least five people who have tested positive for coronavirus after attending a 3 November election night party at the White House.
The others are Housing and Urban Development Secretary Ben Carson, Trump's chief of staff Mark Meadows, advisor David Bossie and White House political director Brian Jack.
Lewandowski told CNN, however, that he may have contracted the virus while in Philadelphia, where he has been mounting legal challenges to President-elect Joe Biden's victory in the state.
Trump was briefly hospitalised with the virus in early October and his wife, First Lady Melania Trump, and their son Barron also came down with Covid-19.
The United States has recorded more than 242 000 deaths from Covid-19 and more than 10.4 million people have been infected.