WASHINGTON – A coronavirus outbreak that infected President Donald Trump and spread to the Senate threw a fresh element of uncertainty into the politically fraught fight over installing Judge Amy Coney Barrett on the Supreme Court before Election Day. Republicans vowed to press ahead and Democrats insisted on a pause.

Pulling off a complex confirmation that touches all three branches of government in the four weeks remaining before the election always promised to be a daunting task for Republicans in the middle of a pandemic. But by Friday evening, with the White House and Congress in turmoil and two Republican members of the Judiciary Committee, Sens. Mike Lee of Utah and Thom Tillis of North Carolina, among those announcing they had tested positive, it was clear that the challenge had grown steeper.

Senate Majority Leader Mitch McConnell said Saturday that the full Senate would not convene until Oct. 19 after a third GOP senator — Ron Johnson of Wisconsin — announced he had tested positive.

But despite the increase in confirmed cases, Republican leaders signaled they had no intention of slowing their ambitious time frame for confirming Barrett before Election Day.

“The Senate’s floor schedule will not interrupt the thorough, fair and historically supported confirmation process previously laid out,” McConnell said in a statement.

A spokesman for the Senate Judiciary Committee said Saturday that the panel would begin four days of confirmation hearings Oct. 12 as planned.

Minority Leader Chuck Schumer condemned McConnell’s decision to press ahead with the proceedings, calling the effort “monomaniacal.”

Top Republicans hope to send her nomination to the full Senate by Oct. 22 and confirm her as soon as Oct. 26, eight days before Election Day — even if it means breaking Senate norms and considering a lifetime judicial nomination by video conference.

It gave Democrats a new reason to call for a delay in confirmation proceedings so close to an election. Seeing a potential opening, top Democrats called for the Senate to pause and assess the scope of the outbreak. They declared that a fully virtual hearing for a candidate for a lifetime appointment would be unacceptable.

“It’s critical that Chairman [Lindsey] Graham put the health of senators, the nominee and staff first — and ensure a full and fair hearing that is not rushed, not truncated and not virtual,” Schumer and Sen. Dianne Feinstein of California, the top Democrat on the Judiciary Committee, said in a joint statement. “Otherwise, this already illegitimate process will become a dangerous one.”

On Friday evening, after Tillis announced his positive test result, Schumer renewed his call for delay, writing on Twitter that going forward with hearings would be “irresponsible and dangerous.”

“There is absolutely no good reason to do so,” he said.

But committee chairman Graham, of South Carolina, vowed he would stick to his schedule.

Republican officials said they had no doubt that senators would find a way to muscle through the nomination over Democrats’ protests. But Republicans cannot afford to have many members sidelined by illness, which could provide Democrats an opportunity to stall the proceedings. Two GOP senators, Susan Collins of Maine and Lisa Murkowski of Alaska, have already raised objections to moving ahead before the election, reducing the wiggle room in the 53-47 Republican majority.

McConnell has insisted throughout the pandemic that the Senate continue to meet in person, but he conceded Friday that keeping Republican senators healthy was crucial to the fate of the nomination.

“I think every precaution needs to be taken because we don’t anticipate any Democratic support at all, either in committee or the full Senate, and therefore everybody needs to be in an all-hands-on-deck mind-set,” he said.