David Bossie, an outside adviser to Donald Trump who is leading his post-election fight over vote counts, has tested positive for coronavirus, according to people familiar with the matter, the latest in a series of cases among the president’s circle.

Bossie, who tested positive on Sunday, joins Housing and Urban Development Secretary Ben Carson and White House Chief of Staff Mark Meadows, who both contracted the virus in the past week.

Bossie was diagnosed during a test on the White House campus. Visitors are required to test before seeing the president.

Trump tapped Bossie to help with post-election strategy last week, after Meadows was diagnosed with the virus on Wednesday.

Trump’s team has filed a number of lawsuits challenging ballot counting and Nov. 3 election results in several states, some of which have been dismissed. The president and his team claim there were widespread irregularities but haven’t provided evidence to back up the assertion.

Democrat Joe Biden won at least the 270 Electoral College votes he needed to secure the presidency, according to the Associated Press. He could win as many 306 if he takes the remaining states where he is ahead, including Georgia, where he currently leads by more than 10,000 votes.

Carson tested positive for coronavirus on Monday morning and is isolating at home after experiencing symptoms of Covid-19, according to a memo obtained by Bloomberg News. HUD’s Chief of Staff Andrew Hughes said in the memo sent to the agency’s staff that Carson was “resting at his house and is already beginning to feel better.”

Bossie, Meadows and Carson attended an election night party on Tuesday at the White House. Meadows tested positive for coronavirus the day after he attended the same party.

Aside from Meadows, at least five other White House officials have tested positive in recent days, as well as a senior Trump campaign adviser.

Several other cabinet chiefs were in attendance at the election night party, including Treasury Secretary Steven Mnuchin, Health and Human Services Secretary Alex Azar, Attorney General William Barr and Interior Secretary David Bernhardt.

Mnuchin tested negative today, according to the Treasury Department. Azar, one of the only people at the party to be photographed wearing a mask, made a morning appearance on Fox News today.

He said he had not been in close contact with Carson at the party.

Barr is negative for the virus, according to his spokeswoman Kerri Kupec. The Justice Department didn’t immediately say when he was last tested.