All eyes are on the final four swing senators who will determine whether Brett Kavanaugh gets a seat on the Supreme Court as the Senate barrels toward a final vote this weekend.

The momentum seemed to be moving in Kavanaugh's direction as Jeff Flake, R-Ariz., told reporters Friday afternoon that he plans to vote to confirm Kavanaugh "unless something big changes."

Flake -- along with Republican Sen. Susan Collins, R-Maine and West Virginia Democratic Sen. Joe Manchin -- voted Friday to advance Kavanaugh's nomination to a final Saturday vote.

"We think things are moving in the right direction and we are optimistic that ultimately, we will get judge Kavanaugh confirmed for the United States Supreme Court," Sen. John Thune, R-S.D., said Friday on Fox News' "Outnumbered Overtime."

But Sen. Lisa Murkowski, R-Alaska, voted against proceeding to the final confirmation vote, in a move suggesting she may vote against Kavanaugh. Fox News has confirmed Murkowski remains undecided.

“I believe we are dealing with issues that are bigger than a nominee,” Murkowski told reporters, calling Kavanaugh nomination's the “most difficult” one she’s ever had to make.

“In my view, he’s not the right man for the court at this time,” she said.

With a 51-49 majority, Republicans can't afford more than one defection if all Democrats were to vote together. A Manchin vote for Kavanaugh, though, would give Republicans some cushion.

Collins is expected to announce her decision in a speech on the Senate floor at 3 p.m. Friday.

SENATE VOTES TO ADVANCE KAVANAUGH NOMINATION

Earlier Friday, the Senate vote to invoke cloture and proceed to a final vote was 51-49. While the vote was not necessarily indicative of the final confirmation vote, it moved him one step closer to sitting on the highest court in the land.

The math for Republicans became somewhat trickier late Thursday when Sen. Steve Daines, R-Mont., said he would be attending his daughter's wedding in Montana on Saturday. He said he would return to cast the decisive vote if needed.

Daines said in a Friday statement that fellow Montana Rep. Greg Gianforte, a friend, offered to let Daines use his plane to get back to Washington to vote, if needed.

“My good friend and colleague, Greg, has come to save the day. If I need to be in two places at once to walk my daughter down the aisle on her wedding day and to be the final vote to put Judge Kavanaugh on the Supreme Court, he’s offered me use of his plane,” Daines said.

President Trump welcomed Friday's vote in a tweet, saying he was "very proud" of the Senate. A source familiar with the lobbying efforts to confirm Kavanaugh told Fox News that the White House believes it has the votes to confirm Kavanaugh.

The source said that the White House believes Murkowski will ultimately be a "no," but Manchin, Collins and Flake will all vote "yes."

Kavanaugh’s nomination was embroiled in a controversy that gripped the nation after multiple women made sexual assault allegations originating from his time in high school and college. The most prominent allegation was from California professor Christine Blasey Ford, who said that Kavanaugh assaulted her at a high school party. That allegation resulted in a high-stakes Senate Judiciary hearing last week where both Ford and Kavanaugh testified.

Democrats said the allegations were credible and deserved a full investigation, while Republicans accused Democrats of using uncorroborated allegations to scuttle or delay the nomination -- leading to a stream of angry flashpoints between lawmakers. The accusations eventually led to President Trump ordering an FBI investigation. Republicans who had seen the FBI’s report said the FBI had produced no credible corroboration of the allegations.

Protesters flooded the Capitol in the days ahead of the vote, and clashed with Republican lawmakers in an effort to sway their votes, and initially appeared to have some success. Flake demanded the limited FBI investigation last week after being cornered in an elevator by screaming protesters moments before a Senate Judiciary Committee vote to recommend Kavanaugh’s nomination.

Senate Majority Leader Mitch McConnell, R-Ky., said that the vote was "a pivotal day for us here in the Senate."

"The ideals of justice that have served our nation for so long are on display," he said, calling the last two weeks a "disgraceful spectacle."

But Democrats had pointed to not only the sexual assault allegations, which they described” but also questions about Kavanaugh’s temperament during the hearing last week and whether he had lied about his drinking during high school and college, and what certain references in his high school yearbook meant. They also sought to paint him as a justice that would swing the court deeply to the right.

Senate Minority Leader Chuck Schumer, D-NY, accused Kavanaugh of being evasive in his answers during his confirmation hearings on key topics. He said his views are “deeply at odds with the progress America has made in the last century of jurisprudence and at odds with what most Americans believe.”