Stephen Miller, one of President Trump's most senior aides, has revealed he has tested positive for coronavirus.
"Over the past five days I have been working remotely and self-isolating, testing negative every day through yesterday," Mr Miller said.
"Today I tested positive for Covid-19 and am in quarantine."
He is the latest staffer to fall victim to the White House Covid-19 cluster.
White House press secretary Kayleigh McEnany revealed on Tuesday that she tested positive for coronavirus, only days after President Donald Trump contracted the disease and was moved to a hospital for treatment.
Mr Trump announced the diagnosis on Friday, the day after White House special adviser Hope Hicks tested positive.
This latest announcement will bring the president's flippant attitude towards face masks under further scrutiny.
Democratic presidential candidate Joe Biden criticised Mr Trump for taking off his mask on his arrival back at the White House on Monday, after spending three nights in hospital being treated for the virus.
Mr Miller’s wife, Katie Miller, a spokeswoman for Vice President Mike Pence, caught the virus in May but recovered.
