By Jill Colvin and Zeke Miller // Associated Press

The White House said Friday that President Donald Trump was suffering “mild symptoms” of COVID-19, as the virus that has killed more than 205,000 Americans spread to the highest reaches of the U.S. government just a month before the presidential election.

The revelation came in a Trump tweet about 1 a.m. after he had returned from an afternoon political fundraiser without telling the crowd he had been exposed to an aide with the disease that has infected millions in America and killed more than a million people worldwide.

First lady Melania Trump also tested positive, the president said, and several others in the White House have, too, prompting concern that the White House or even Trump himself might have spread the virus further. The Trumps’ son Barron, who lives at the White House, tested negative.

Trump has spent much of the year downplaying the threat of the virus, rarely wearing a protective mask and urging states and cities to “reopen” and reduce or eliminate shutdown rules.

Both Democratic presidential nominee Joe Biden and his running mate Kamala Harris have tested negative, their campaign said. Vice President Mike Pence tested negative for the virus Friday morning and “remains in good health,” his spokesman said.

Trump’s Supreme Court nominee, Judge Amy Coney Barrett, who was with him and many others on Saturday and has been on Capitol Hill meeting with lawmakers, also tested negative, the White House said.

Trump’s diagnosis was sure to have a destabilizing effect in Washington and around the world, raising questions about how far the virus has spread through the highest levels of the U.S. government. Hours before Trump announced he had contracted the virus, the White House said a top aide who had traveled with him during the week had tested positive.

“Tonight, @FLOTUS and I tested positive for COVID-19. We will begin our quarantine and recovery process immediately,” Trump tweeted just before 1 a.m. “We will get through this TOGETHER!”

While House chief of staff Mark Meadows on Friday tried to assure the public that Trump was conducting business as usual, even as he confirmed that the White House knew Hope Hicks, the aide, had tested positive before Trump attended a Thursday fundraiser in New Jersey.

“I can tell you in terms of Hope Hicks, we discovered that right as Marine One was taking off yesterday,” said Meadows. Several staffers were pulled from the trip, but Trump did not cancel, even after having been exposed to Hicks.

Many White House and senior administration officials were undergoing tests Friday, but the full scale of the outbreak around the president may not be known for some time as it can take days for an infection to be detectable by a test. Officials with the White House Medical Unit were tracing the president’s contacts.

Trump was considering how he might address the nation or otherwise communicate with the American people Friday, an official added.

Trump was last seen by reporters returning to the White House on Thursday evening and did not appear ill. He is 74 years old and clinically obese, putting him at higher risk of serious complications from a virus that has infected more than 7 million people nationwide.

The president’s physician said in a memo that Trump and the first lady, who is 50, “are both well at this time” and “plan to remain at home within the White House during their convalescence.”

Trump has been trying all year to convince the American public that the worst of the pandemic is behind them. In the best of cases, if he develops few symptoms, which can include fever, cough and breathing trouble, it will likely force him off the campaign trail just weeks before the election and puts his participation in the second presidential debate, scheduled for Oct. 15 in Miami, into doubt.

Trump’s handling of the pandemic has already been a major flashpoint in his race against Biden, who spent much of the summer off the campaign trail and at his home in Delaware citing concern about the virus. Biden has since resumed a more active campaign schedule, but with small, socially distanced crowds. He also regularly wears a mask in public, something Trump mocked him for at Tuesday night’s debate.

“I don’t wear masks like him,” Trump said of Biden. “Every time you see him, he’s got a mask. He could be speaking 200 feet away from me, and he shows up with the biggest mask I’ve ever seen.”

In a tweet Friday morning, Biden said he and his wife “send our thoughts to President Trump and First Lady Melania Trump for a swift recovery. We will continue to pray for the health and safety of the president and his family.”

World leaders offered the president and first family their best wishes after their diagnosis, as governments used their case as a reminder for their citizens to wear masks and practice social distancing measures.