Trump’s Covid-19 Symptoms Are Said to Be ‘Very Concerning’

In a statement on Friday, Dr. Conley said that Mr. Trump received the antibody cocktail “following PCR-confirmation of the president’s diagnosis.” But if he started it 48 hours earlier, as Dr. Garibaldi said on Saturday, that would mean he had begun treatment by midday on Thursday, before the PCR test that Dr. Conley said came in late Thursday night, and before he flew to New Jersey for a fund-raising event at his golf club.

Melania Trump, the first lady, who also is sick, remained at the White House while the rest of the president’s family members have tested negative but were being retested to confirm those results since it can take some time before the virus is detectable.

“Thanks to all those who so lovingly have reached out about @realDonaldTrump and the rest of the family,” Donald Trump Jr., the president’s eldest son, tweeted on Saturday morning. “It truly means a lot to us. I tested negative so I’ll give it a few more days out of and abundance of caution and test again and if I’m clear I’ll be back to work asap.”

Two of the three senators who have now tested positive for the virus, Mike Lee of Utah and Thom Tillis of North Carolina, were at the Barrett announcement and serve on the Senate Judiciary Committee that will consider her nomination, further complicating a confirmation drive that was already testing speed limits and a razor-thin majority to get done before the election, as Mr. Trump has insisted.

Mr. Johnson, the third senator now infected, was not at the event because he was quarantining from a previous exposure to someone with the virus. He emerged from 14 days of quarantine after testing negative and returned to Washington on Tuesday, his office said, but attended lunch with other Senate Republicans that put him in the same room with Mr. Lee and Mr. Tillis. He was tested again on Friday.

If all three Republicans were unable to vote, then Senator Mitch McConnell, the Republican majority leader from Kentucky, would not have enough support to force through confirmation of Judge Barrett. Because two moderate Republican senators, Susan Collins of Maine and Lisa Murkowski of Alaska, have already indicated that they oppose installing a new justice before the election, that would leave Mr. McConnell with 48 Republicans to 47 Democrats and the two dissenting Republicans.

But even as Mr. McConnell said on Saturday that the full chamber would not meet this coming week as planned, Republican leaders vowed to push ahead with the confirmation on the hope that the infected senators would not get sick and therefore be able to return in time for a pre-election vote. Senator Lindsey Graham, Republican of South Carolina and chairman of the Judiciary Committee, issued a statement saying the panel would proceed with plans to meet on Oct. 12 to begin considering Judge Barrett’s nomination.