Amy Coney Barrett's nomination to the Supreme Court broke through one more hurdle ahead of her all-but-assured confirmation to replace the late Justice Ruth Bader Ginsburg as Democratic senators ramped up their criticism of the conservative judge. 

The vote to end a filibuster on her nomination, which occurred around 1:30 p.m. ET Sunday, was 51-48. Two GOP senators - Susan Collins of Maine and Lisa Murkowski of Alaska - voted with Democrats to oppose Barrett's nomination from advancing, although Murkowski plans to support the federal appeals court judge on the confirmation vote on Barrett's merits.

If confirmed, Barrett will be the third Supreme Court pick from President Donald Trump.

The final confirmation vote for Barrett is expected sometime Monday night, putting her in position for a first full day as a justice as early as Tuesday and as the court continues to hear election-related legal challenges ahead of Nov. 3.

But the ongoing COVID-19 pandemic, which had intertwined at multiple points with Barrett's nomination, intersected with her confirmation fight once again as several aides to Vice President Mike Pence, including his top staffer, tested positive for the coronavirus.

Pence is the president of the Senate and is regularly summoned to the Capitol to preside over major votes for the administration, or if he needs to break a tie. A spokesman for the vice president's office did not respond to inquiries Sunday as to whether Pence planned to attend the Monday night vote.

But at a campaign rally in Tallahassee, Fla., on Saturday evening, the vice president made his intention clear to be present for the confirmation vote for Barrett, who will not only be the administration's third successful Supreme Court confirmation but also hails from Pence's home state of Indiana.

"As vice president, I'm president of the Senate. And I'm gonna be in the chair because I wouldn't miss that vote for the world," Pence said Saturday night at the Florida rally. "And I'll make you a prediction. Come this Monday night, Judge Amy Coney Barrett is going to be Justice Amy Coney Barrett. We're gonna fill that seat."

While Pence has had close contact with Marc Short - his chief of staff who tested positive for COVID-19 - aides said the vice president will not quarantine and instead continue his pre-scheduled events since he is considered essential personnel.

Senate Majority Leader Mitch McConnell, R-Ky., who has been highly critical of how the White House has not abided by public health guidelines on its property, on Sunday declined to answer multiple times whether he preferred Pence stay away from the Capitol for the confirmation vote.

But Senate Minority Leader Charles Schumer, D-N.Y., warned his ranks to limit their time in the Senate chamber amid the news of the fresh outbreak on Pence's staff, as well as some reports of infections in the offices of Republican senators.

Republican Georgia Sen. Kelly Loeffler's office said two of her aides have tested positive for COVID-19, but that Loeffler herself had tested negative. Asked Sunday whether she had close contact with those aides - which, under Centers for Disease Control and Prevention guidelines, would require a 14-day quarantine for Loeffler - the senator said: "Not at all."

"Their carelessness with the health and safety of their colleagues and Capitol employees mirrors their carelessness with the health and safety of Americans during this crisis," Schumer wrote in a letter to senators on Sunday. "Therefore, considering the Republicans' refusal to follow CDC guidelines regarding quarantining and contact tracing, I would recommend that you not congregate in the Senate chamber today and that you cast your votes quickly and from a safe distance."

Republican senators downplayed any potential risk that Pence's physical presence may pose in the Capitol on Monday.

"Mike's responsibility is to be here to preside over the Senate. I think the vice president will think he'll do that safely," said Sen. Mike Rounds, R-S.D. "Most certainly, I think he's a very responsible individual and I think he will do it according to the best practices as recommended by the physician."

A vast majority of senators wear masks, have ordered most of their staff to work remotely and at least try to social distance in the Capitol.

Democrats have criticized the rush to confirm Barrett so close to the election after Republicans blocked the President Barack Obama's Supreme Court nomination for months in 2016.

"The Republicans, as we all know, as the nation knows, are running the most partisan, most hypocritical, least legitimate process in the history of Supreme Court nominations," Schumer said Friday.

Democrats also have cast Barrett, a 48-year-old conservative jurist, as a threat to the Affordable Care Act, abortion rights and gay rights.

A series of overnight speeches from senators is also expected ahead of the confirmation vote.