Two Republican senators on the pivotal Judiciary Committee have tested positive for the coronavirus after attending White House events last week announcing Mr. Trump’s nominee for the Supreme Court, Judge Amy Coney Barrett, throwing the future of her Supreme Court confirmation hearings into question.
The senators, Thom Tillis, Republican of North Carolina, and Mike Lee, Republican of Utah, both of whom announced their test results on Friday, are among several people who have tested positive since attending the events last Saturday.
Others include Bill Stepien, President Trump’s campaign manager; Melania Trump, the first lady; John I. Jenkins, the president of the University of Notre Dame; and Kellyanne Conway, the former top White House adviser, who left her post over the summer. Ms. Conway announced her positive result in a Twitter post late Friday night.
The Sept. 26 Rose Garden ceremony for Judge Barrett was most likely not a “super-spreader” event, because it was outdoors. However, many top Republicans attended without masks or social distancing, raising concerns that others might have contracted the virus but had not yet been diagnosed. And someone who was infected and did not have symptoms could have transmitted the virus to others during indoor discussions inside the White House.
Leading Republicans said they planned to continue “full steam ahead” to confirm Judge Barrett before Election Day. But Mr. Trump’s illness, along with the fact that Senator Tillis and Senator Lee sit on the Judiciary Committee, has raised questions about whether the party’s extraordinarily ambitious timetable could hold.
Mr. Tillis’s diagnosis also dealt a blow to Republicans’ hopes of retaining control of the Senate, given that he was already facing a difficult re-election battle.
Top Senate Democrats demanded on Friday that Republicans slow their timetable for confirming Judge Barrett, saying that if Republicans proceed with hearings without an understanding of the full extent of the virus’s spread from the Sept. 26 events, an “already illegitimate process will become a dangerous one.”
Senator Chuck Schumer of New York, the Democratic leader, responding to Senator Tillis’s announcement on Friday evening that he had “no symptoms” but would quarantine for 10 days at home, called on Republicans to delay the confirmation hearings.
“We now have two members of the Senate Judiciary Committee who have tested positive for Covid, and there may be more. I wish my colleagues well,” Mr. Schumer said. “It is irresponsible and dangerous to move forward with a hearing, and there is absolutely no good reason to do so.”
The confirmation of a sixth conservative-leaning justice to the court would be the culmination of a decades-long conservative project, an effort spearheaded by the majority leader, Senator Mitch McConnell of Kentucky.
Judge Barrett, 48, tested negative on Friday, a White House official said. Two officials with knowledge of her medical history said that she had already had the coronavirus and recovered earlier this year.
Judge Barrett was in close contact with Mr. Trump at the White House last weekend. She also worked closely with several White House officials and met with dozens of Republican senators on Capitol Hill, including Senator McConnell and Senator Lee.
A video posted on Twitter showed Senator Lee hugging people at the event. He said he had tested negative at the White House on Saturday.
It can take several days for someone who has been exposed to the virus to develop symptoms or to test positive. Anyone tested within just a day or two of exposure is likely to receive a negative result even if they are infected.
Senator Lindsey Graham of South Carolina, the Judiciary Committee chairman, said on Friday that his panel would begin four days of public hearings on Judge Barrett’s nomination on Oct. 12, as scheduled. Senator Tillis and Senator Lee said they would isolate for 10 days, which would enable them to emerge in time for the hearings.
In an interview on Friday, Senator McConnell suggested that the virus’s spread through Republican circles could mean that more lawmakers would participate in the hearings virtually. “This sort of underscores the need to do that,” he said.
But Democrats said that virtual hearings on such a consequential matter would be unacceptable.