Weeks of tumult and testimony, allegations and anger, pain and postponement over President Donald Trump's Supreme Court nominee Brett Kavanaugh, it is still all about four undecided senators . There will be ample time to figure out what this nomination means -- for the Senate, for the court, for this moment, for the election, for the country. But on Friday, it's all about the math: Can Senate Majority Leader Mitch McConnell get 50 senators to "yes"?

Bottom line: Republicans do not have the votes as of dawn Friday morning, according to people with direct knowledge.

McConnell is heading into the day that could clinch one of, if not the, cornerstone achievements of his career -- tilting the court's makeup firmly to the conservative side -- and he doesn't currently have the votes. He and his top deputies are optimistic, no question. But it's not there yet.

Key undecided senators -- including West Virginia Democrat Joe Manchin and Maine Republican Susan Collins -- maintained they were undecided on Friday morning and won't make their decision known until they're on the Senate floor.

The schedule

The Senate gaveled into session at 9:30 a.m. ET.

The vote to end debate (cloture) on Kavanaugh's nomination is scheduled for 10:30 a.m. ET.

To make it clear: Friday's vote is procedural -- Republicans need a simple majority to end debate -- also referred to on Capitol Hill as invoking cloture. But make no mistake about it -- this is the ballgame. Senators aren't going to flip their votes between Friday and Saturday. Kavanaugh's future as a Supreme Court justice will be decided in the coming hours.

What to watch: The expectation is that the undecided senators will release statements and/or go the floor to announce their intentions before the vote.

The math

McConnell has 48 senators in the "yes" camp. If two of the remaining undecided voters decide to join them, Vice President Mike Pence will come break the 50-50 tie. If three or more come over to the "yes" side, Pence won't be needed (but it may have implications for when Kavanaugh is actually confirmed -- see below).

The view from senior GOP officials and senators, as of Thursday night: Throughout the past 24 hours, Republican officials grew more confident that Collins and Republican Sen. Jeff Flake of Arizona would come their way. Republican Sen. Lisa Murkowski of Alaska is viewed as the most on-the-fence member of the four undecided. Manchin, who reviewed the FBI report again Friday morning, is considered getable by Republicans, but largely dependent on where the three GOP senators go first.

Technical point

Senators can change their votes between Friday and Saturday. They are two different votes, and in the past, senators have voted to advance a bill or nomination as a favor to leadership, only to vote against that bill or nomination when it reaches its final stage. It's something the late Arizona Republican Sen. John McCain was often willing to do as a hat tip to leadership. Senior GOP aides have been skeptical it would occur in this case -- a nomination, unlike a bill, doesn't leave open the possibility of future changes via amendment or conference committee with the House. It is yes or no. Up or down. But it's not out of the realm of possibility -- and something to keep an eye on as the day moves forward.

McConnell's reasoning

Heading into a vote of this magnitude without having the votes locked into place is pretty much the last thing the guy who wrote a book titled "The Long Game" would want to do. But the reality, as described by people involved in the process, is that it's viewed internally as the only play at this point.

Multiple hearings, delays and an FBI supplemental background investigation have prolonged the process. New allegations or interviews from former friends or roommates have hit Kavanaugh daily. And for undecided senators, a binary choice that isn't going to change -- or get easier -- with more time.

In other words, the decision has been made that it's time to make everyone put their cards on the table. It's a risk -- senators historically don't take too kindly being called on the carpet before they're ready to make up their minds. And while technically Friday's procedural vote could fail and they could try again, it's almost inconceivable that another run at it would change votes.

"It's time," one GOP official said. "It's never going to get any easier, so it's time to pull the trigger and get this done."

And if they don't have the votes? "Honestly, who the hell knows."

The Undecideds

Murkowski: Murkowski was scheduled to go back in to review the FBI report late Thursday evening. While she wasn't spotted by CNN, two senators she is friendly with were -- Sens. Jim Risch of Idaho and John Hoeven of North Dakota. Murkowski reviewed the report multiple times on Thursday and largely avoided reporters.

Collins: Collins said Friday that she'll vote for the procedural maneuver to advance Kavanaugh, but said she won't announce her final vote until the afternoon. She gave GOP leaders an early boost when she Collins said Friday that she'll vote for the procedural maneuver to advance Kavanaugh, but said she won't announce her final vote until the afternoon.She gave GOP leaders an early boost when she said the FBI report appears to be "very thorough." She completed her review of the materials Thursday night.

Flake: Flake gave another boost to GOP leaders saying he didn't hear "additional corroboration" of the Kavanaugh allegations in the first staff briefing. But he too largely went silent and avoided reporters the rest of the day. Sources with knowledge of how he approached the day tell me he is not as skittish as some were reporting about his final decision. But he did want to make sure he went thoroughly through the report he was essentially responsible for existing. Sources told CNN's Dana Bash that Flake was calling close confidantes on Friday morning to talk through his options.

Manchin: "Heidi made her decision. I'll make mine." That's what Manchin said when asked about the decision by Sen. Heidi Heitkamp, another red state Democrat who voted for Justice Neil Gorsuch, to oppose Kavanaugh. The cross-current pressures are intense between his party, his state, and the nominee himself. On Friday morning, he told reporters that he was still undecided and a Manchin aide told CNN's Manu Raju that he'll announce his decision on the Senate floor later in the day.

Senators are people, too

Sen. Steve Daines, a Montana Republican, has somewhere to be on Saturday -- and it's not on the Senate floor. Daines informed Republican leadership this week that he planned to walk his daughter down the aisle for her wedding, no matter the vote schedule, on Saturday.

This won't change the outcome -- but it could make things take a lot longer. Daines told CNN's Ted Barrett last night he'll come back after the wedding to vote, if he's needed. And he spoke to Kavanaugh by phone Thursday night to tell him he'd be there for him, his spokeswoman said.

But McConnell can't technically move the vote; once the 30 hours of post-cloture time expires, the vote is called. So his only option, if he needs Daines to get to 50, would be to leave it open until he returns.

Will that happen? That all depends on Friday -- if McConnell has 51 votes, then Daines' absence won't matter. If he only has 50? Prepare for a long day Saturday (and into Sunday).