Sen. Mitt Romney (R-Utah) signaled on Tuesday that he is open to confirming a Supreme Court nominee this year, solidifying GOP support for Senate Majority Leader Mitch McConnell's (R-Ky.) vow to hold a vote on President Trump's nominee.

“The Constitution gives the President the power to nominate and the Senate the authority to provide advice and consent on Supreme Court nominees. Accordingly, I intend to follow the Constitution and precedent in considering the President’s nominee. If the nominee reaches the Senate floor, I intend to vote based upon their qualifications," Romney said in a statement.

Romney's decision is a blow to Senate Democrats and a boon to McConnell, with both sides watching him closely as a potential swing vote on bringing up whomever Trump nominates to fill the late Justice Ruth Bader Ginsburg's seat just weeks before a presidential election.

McConnell has essentially locked down support within his 53-member caucus to move a Supreme Court nominee this year, laying the groundwork for an explosive fight that critics warn could lead to an overhaul of the Senate. McConnell has not said if he will try to move a nomination before or after the election.

Sen. John Thune (R-S.D.), McConnell's No. 2, said on Tuesday after Romney's announcement that he personally supports moving Trump's nominee before the election, but the decision on timing will need to be discussed with the caucus during a closed-door lunch later Tuesday. 

“Speaking for me personally? Yes. I think it would be a good idea for us to move forward. But obviously we have a lot of different members who might have different positions. We’ll get an assessment of that. At least we’re hearing from everybody, everybody wants to move forward," Thune said. 

Thune added that leadership has been talking with members since Friday night.

"I think people are very supportive of the idea of moving forward. In terms of the timing, that’s still up in the air," he said.

With 53 members, Republicans could lose three senators and still let Vice President Pence break a tie on a Supreme Court nomination. If Pence breaks a tie, that would be the first time a vice president has had to weigh in on a Supreme Court pick.

So far only two GOP senators have said they do not support moving a nomination before the Nov. 3 election: Sens. Susan Collins (Maine) and Lisa Murkowski (Alaska).

To stop McConnell successfully, Democrats will need four GOP senators to side against him, an uphill battle given the growing partisanship over the courts, which is a top issue for the Republican base.

And the pool of GOP senators who could side with Democrats on the process argument appears to have closed. Several Republicans considered vulnerable this fall, including Sens. Cory Gardner (Colo.) and Joni Ernst (Iowa), have signaled they are on board with McConnell's plan, though they've said that they will make a decision on confirmation once Trump nominates a judge.

Republicans have a matter of weeks if they want to confirm Trump’s nominee before the election. The president isn’t expected to name his pick until Saturday, which will be 38 days before Nov. 3. According to the Congressional Research Service, the average number of days from nomination to final Senate vote is 69.6. 

But there are vocal supporters within the caucus of getting Trump’s nominee through the Senate before November, and risks to waiting until the lame-duck session, which would raise new questions if Republicans lose the Senate majority or Democratic nominee Joe Biden wins the White House. 

“I've seen this move before. It's not going to work. ... We've got the votes to confirm Justice Ginsburg's replacement before the election,” Senate Judiciary Committee Lindsey Graham (R-S.C.) told Fox News on Monday night.

Romney had been expected to wait until after the closed-door caucus lunch to make his decision ahead of announcing his decision.

But the former governor told reporters on Tuesday morning that he had spoken to a number of his colleagues.

"I recognize that we may have a court that has more of a conservative bent ... but my liberal friends have, over many decades, gotten very used to the idea of having a liberal court and that's not written in the stars," he said.

Romney declined to talk about hypotheticals, including how he would handle a Supreme Court nominee during a lame-duck if Democrats win back the majority in November or if Biden takes the White House.

Democrats have accused Republicans of hypocrisy for being willing to move Trump's forthcoming nominee weeks before the election when they refused to move then-President Obama's final Supreme Court nominee, Merrick Garland, months before the 2016 election.

Republicans have argued, and Romney appeared to agree on Tuesday, that the difference between divided government between the Senate and White House in 2016 and unified control of the Senate and the White House in 2020 is a key distinction.

“My decision regarding a Supreme Court nomination is not the result of a subjective test of ‘fairness’ which, like beauty, is in the eye of the beholder. It is based on the immutable fairness of following the law, which in this case is the Constitution and precedent. The historical precedent of election year nominations is that the Senate generally does not confirm an opposing party’s nominee but does confirm a nominee of its own," Romney said in his statement.

Senate Minority Leader Charles Schumer (D-N.Y.) ripped into Republicans and Trump from the Senate on floor on Tuesday, arguing that they were violating the “McConnell rule,” after refusing to give Garland a hearing or a vote.

"Leader McConnell has defiled the Senate like no one in this generation, and Leader McConnell may very well destroy it,” Schumer said. 

Updated at 10:56 a.m.