White House chief of staff Mark Meadows tested positive for Covid-19, a source familiar with the diagnosis told NBC News on Friday.
It also comes as President Donald Trump and some of his allies are mounting election-related lawsuits and making baseless claims of voter fraud to fight off the prospect of a Joe Biden presidency.
It is not immediately clear when Meadows tested positive.
Trump named Meadows his new chief of staff in March. Meadows, 61, a former North Carolina congressman and onetime leader of the House Freedom Caucus, is a longtime Trump loyalist.
Meadows was among those in attendance Wednesday morning hours after the polls closed for an election night party at the White House, where Trump falsely claimed that he had won the presidential election as millions of votes had yet to be counted and several battleground states were not called.
Many attendees, such as Fox News personalities and White House aides, were seen not wearing masks as they ate and mingled before the president’s speech.
Nick Trainer, a Trump campaign aide, also tested positive, bringing the total of people inside the president's orbit known to have contracted Covid-19 to 35.
Trainer is the director of battleground strategy for Trump's re-election effort. It’s unclear when he contracted the virus and when he was last at campaign headquarters in Virginia.
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The Trump campaign declined to comment.
Prior to these cases, 28 administration officials, campaign officials and close contacts tested positive for the virus during a late-September and early October outbreak in the White House. Among those cases, at least 14 were people who attended the Sept. 26 Rose Garden event for Supreme Court Justice Amy Coney Barrett.
Trump and first lady Melania Trump tested positive for Covid-19 after White House aide Hope Hicks was diagnosed last month, among other high-profile Republicans in the White House, Congress and the Trump campaign. Many, including the president, have since recovered.