Republicans have signaled that they’ll move forward with a nominee to replace Supreme Court Justice Ruth Bader Ginsburg, despite their 2016 comments on not replacing a justice in a presidential election year.

But that doesn’t necessarily mean they’ll actually have the votes to do so.

As noted upon the vacancy on Friday, the GOP has an effective 53-to-47 majority in the Senate, and with a 50-vote threshold (plus Vice President Pence breaking ties), four GOP “no” votes would probably mean the nominee fails. That margin for error could be reduced if Republicans wait till the lame-duck session after the election, if Democrats defeat appointed Sen. Martha McSally (R-Ariz.), given her replacement could be seated in November.

So what about the key potential GOP votes against the eventual nominee? What have they said, and what are their political motivations? Let’s recap.

Lisa Murkowski

The Alaska GOP senator has been firmer than anyone in saying she doesn’t support moving forward. “I did not support taking up a nomination eight months before the 2016 election to fill the vacancy created by the passing of Justice [Antonin] Scalia,” she said this weekend. “We are now even closer to the 2020 election — less than two months out — and I believe the same standard must apply.”

Murkowski has regularly been a tough vote for the GOP, dating back to when she lost her 2010 GOP primary but was reelected as a write-in candidate. But that has especially been the case in the Trump era, in which Murkowski has often been one of the potential and actual swing votes, including on the GOP’s Obamacare replacement, which she voted against. She was also one of the GOP senators who held out for more information from the FBI about allegations of a decades-old sexual assault against Brett M. Kavanaugh during his 2018 confirmation. She wound up opposing Kavanaugh but voted “present,” she said, to offset a GOP senator who wasn’t able to make the vote but supported Kavanaugh.

She has perhaps less obvious political motivations to oppose the nominee here, in that she comes from a red state and could be creating problems for herself in her 2022 reelection bid. But she has repeatedly held out on similar issues and has criticized President Trump.

Susan Collins

Collins (R-Maine) is the other apparent holdout. She said this weekend, “Given the proximity of the presidential election … I do not believe that the Senate should vote on the nominee prior to the election. In fairness to the American people, who will either be reelecting the President or selecting a new one, the decision on a lifetime appointment to the Supreme Court should be made by the President who is elected on Nov. 3.”

Collins’s calculus is more complicated than Murkowski’s, in that she is up for reelection this year in a very difficult race on that same date. A Suffolk University poll released Monday showed Democrat Sarah Gideon leading her 46 percent to 41 percent, and others have shown her deficit as big as double digits.

But as with any Republican facing reelection this year, the balance is between appealing to the middle — which is huge in Maine — and alienating base Republican voters. Collins’s comments have been somewhat more qualified than Murkowski’s, in that she’s said there shouldn’t be a vote rather than that she wouldn’t support the nominee. She has also suggested a vote shouldn’t come before the election — when it might be more politically troublesome for her — while not always necessarily saying it shouldn’t come during the lame-duck session between the election and when new senators and a president are sworn in. (Her most recent comments suggest that she opposes that too, though.)

This may feel like over-parsing, but politicians choose their words carefully for a reason. And a confirmation after Election Day would be much easier for Collins, who unlike Murkowski voted for Kavanaugh in 2018 and would be freed of immediate electoral concerns come Nov. 4.

Mitt Romney

The third most-likely holdout would seem to be the Utah senator, who in February became the only member of a president’s party to ever vote to remove them from office following an impeachment trial. Romney has also staked out principled stands against Trump on numerous occasions. And he has recently thrown a wrench in Republicans’ effort to investigate Hunter Biden, suggesting it’s transparently political.

But to this point, he’s been notably quiet about the Supreme Court vacancy. And his office notably shot down an Internet rumor that he would not confirm a nominee until after Inauguration Day.

That doesn’t mean Romney will be on board, necessarily. But his lack of comment is notable and suggests he’s keeping his powder dry.

As with Murkowski, the political motivation is less evident, given that Romney comes from a red state (albeit one that, thanks to its heavy Mormon population, has resisted Trump more than other similar states). Romney has also shown that he’s willing to take principled positions against Trump that might hurt him in his state and with the broader Republican Party. But one key difference with the two female GOP senators above is this: They are more moderate on abortion rights, and opposing a potential Supreme Court nominee who might vote against Roe v. Wade on procedural grounds could make their eventual vote on such a pivotal nominee simpler.

To the extent Collins and Murkowski have come out against this looming nomination, they’ve increased pressure on Romney as a potential swing vote — one that could potentially push this to a 50-50 vote.

Charles E. Grassley

Grassley (R-Iowa) has been pretty clear about his concern about proceeding with a nominee in a presidential election year. In his previous role as Senate Judiciary Committee chairman, he had more control over that. But he’s still a vote that, if the GOP lost him, would probably torpedo the nominee.

“If I were chairman of the committee and this vacancy occurred, I would not have a hearing on it because that’s what I promised the people in 2016,” Grassley said in July.

That’s not to say he would be expected to oppose whomever that nominee is. But given that retiring Sen. Lamar Alexander (R-Tenn.) has given this gambit the go-ahead, Grassley is perhaps the one GOP graybeard who could potentially oppose this on procedural and institutional grounds.

Grassley is reportedly set to issue a statement Monday. One probably shouldn’t hold one’s breath, though.

Update: Grassley in a statement ignored his previous comments on not taking up the nomination, saying he’ll evaluate the nominee on their merits and attacking Democrats for how they’ve handled previous nominations.

Cory Gardner

The Colorado GOP senator, like Collins, faces a difficult reelection bid this year, with most recent polls showing him trailing by statistically significant margins.

Unlike others in somewhat-less-tough races, though (including Iowa’s Joni Ernst and North Carolina’s Thom Tillis), he has yet to give the go-ahead to pressing forward. His statement Friday night only dealt with his condolences on Ginsburg’s death and her stature in American history.

Here’s what he said in 2016: “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.” (The election is even closer this time — a full seven months closer.)

To the extent Gardner is trying to make a comeback in his reelection bid, voting against a nominee might make sense to give him some moderate cred. But the pressure to fall in with one’s party is often immense, and you have to wonder if he’d ever ultimately ever be a decisive vote — especially given his lack of comment thus far.

Update: Gardner also says he’ll judge the nominee on their merits, without raising a procedural objection.