Senate Majority Leader Mitch McConnell (R-Ky.) said the Senate would vote to confirm a Trump nominee to succeed Justice Ruth Bader Ginsburg in a statement released an hour after her death, but it's unclear whether he can convince a majority of his colleagues to do so.

While several GOP senators on Friday evening were saying that a vote should go forward, some were notably silent on the issue.

McConnell can only afford three defections on what would be one of the most controversial Senate votes in history.

Two key Republican moderates, Sens. Lisa Murkowski (R-Alaska) and Susan Collins (R-Maine), released statements mourning Ginsburg, but did not mention a Senate vote on a Trump nominee.

The two have previously indicated they would not support filling a vacancy weeks before the election. Collins is up for reelection in less than two months, and is badly behind in polls. A key issue in her campaign is her vote to confirm Justice Brett Kavanaugh to the court.  

Murkowski told The Hill over the summer that attempting to fill a Supreme Court vacancy right before the November election or during a lame-duck session in December would create “a double standard” and she “would not support it.”

Murkowski pointed to Senate Republicans' decision in 2016 to keep vacant the seat of late conservative Justice Antonin Scalia until a new president was elected in that year’s election. Then-President Obama nominated D.C. Circuit Court of Appeals Judge Merrick Garland to fill Scalia’s vacant seat in March of 2016 but he never received a Senate Judiciary Committee hearing or a vote.

“When Republicans held off Merrick Garland it was because nine months prior to the election was too close, we needed to let people decide. And I agreed to do that. If we now say that months prior to the election is OK when nine months was not, that is a double standard and I don’t believe we should do it,” Murkowski said. “So I would not support it.”

Another key vote is Sen. Mitt Romney (Utah), the only Senate Republican to vote to convict Trump on an article of impeachment.

Romney also released a statement Friday that mourned Ginsburg, but gave no clues on his feelings about a Senate confirmation vote ahead of the presidential election. 

He declined earlier this year to say what he would do if a Supreme Court seat became vacant before Election Day.

“I’m not at a point where I have something to say,” he said.

It's not clear if any other Republicans might waver on voting to confirm a Trump nominee to replace Ginsburg ahead of the election, though GOP senators in Iowa, North Carolina, Colorado and Montana will all have to consider the decision in the context of toss-up Senate races this fall.

Sen. Martha McSally (Ariz.), the most endangered GOP senator up for reelection this fall, tweeted that the current Senate should vote on a Trump nominee. Other GOP senators, including Texas Sen. Ted Cruz, also called for the current Senate to vote before Election Day.

Sen. Cory Gardner (R-Colo.), who like Collins is running in a state where Biden is expected to win, in 2016 expressed support for keeping the Scalia seat vacant so that voters could have an influence on the future composition of the court.

“In 1992, even then-Senator Joe Biden stated the Senate should not hold confirmation hearings for a Supreme Court nominee until after that year’s presidential election. Our next election is too soon and the stakes are too high; the American people deserve a role in this process as the next Supreme Court Justice will influence the direction of this country for years to come,” Gardner said in March 2016.

It has taken an average of 74 days to confirm the last 10 justices appointed to the Supreme Court, ranging from 99 days for Clarence Thomas in 1991 to 50 days for Ginsburg in 1993.

Election Day is 46 days away and the newly elected Congress is not scheduled to come into session for another 107 days.

Democratic operatives on Friday sought to put pressure on another vulnerable Republican facing reelection, Sen. Steve Daines (R-Mont.), by circulating his statement in 2016: “I don’t think it’s right to bring a nominee forward in an election year.” 

Other Senate Republicans have expressed uncertainty about whether a Supreme Court vacancy should be filled immediately before the election or during a lame-duck session, including Senate Judiciary Committee Chairman Lindsey Graham (R-S.C.).

Graham told The Hill in July that it would depend on where members of the Senate GOP conference stood on the question.

“We’ve got to see where the market is, what other senators think,” he said.

Graham said he’d be “willing” to fill a vacancy, but cautioned: “I’d like to get input from my colleagues.”

Sen. Chuck Grassley (R-Iowa), who was the chairman of the Senate Judiciary Committee in 2016 when Garland was blocked from getting a hearing, said that in theory the Senate should be consistent in how it handles election-year nominations to the high court.

“In the abstract,” he told The Hill this summer. “I would do the same thing in 2020 that I would in 2016.”

But the senior Iowa senator didn’t lay down any hard and fast rule of what should happen should a vacancy arise before Nov. 3. He said the decision would be up to Graham as the current chairman of the Judiciary panel. 

Collins will be among the most-watched GOP senators.

Collins told New York Times reporter Jonathan Martin earlier this month in Maine that she would not support seating a new justice in October.

“I think that’s too close, I really do,” she said, according to a tweet Martin posted Friday evening.

Collins also told the reporter that she would oppose seating a justice during a lame-duck session if Trump loses re-election.

It is difficult to guess at some of the decisions for senators, who will have to weigh a number of issues.

While Romney is not a Trump fan, he has declared support in the past for overturning Roe v. Wade, the landmark case that established abortion rights, and hails from a conservative state.

He would presumable prefer the vacant court seat be filled by a Republican, even if it is Trump, instead of Joe Biden, who has a chance of capturing the White House.

But unlike some other Senate Republicans, Romney has not been a life-long opponent of abortion rights.

When he ran against Sen. Ted Kennedy (D-Mass.) for Senate in 1994, Romney said policy makers “should sustain and support” Roe v. Wade as a well-established law.

“I sustain and support that law and the right of a woman to make that choice,” he said at the time.