(CNN) The Senate showdown over whether Brett Kavanaugh should sit on the Supreme Court is rapidly coming to a head. The FBI delivered its five-day supplementary background check to the Senate in the early hours of Thursday, and now senators are filing into a secure room to read it. (I say "it" because apparently, there is only one copy of the report.)

On Friday, around 11 a.m. ET, the Senate plans to vote to end debate on the Kavanaugh nomination and set up a full floor vote (aka invoke cloture). That final vote on whether Kavanaugh makes the court should be on Saturday.

Between now and then, there's going to be a WHOLE lot of spin about a) what's in the report and b) what it means (or should mean) for Kavanaugh's confirmation.

"This is now the 7th time the FBI has investigated Judge Kavanaugh," President Donald Trump tweeted on Thursday morning. "If we made it 100, it would still not be good enough for the Obstructionist Democrats." Senate Judiciary Chairman Chuck Grassley, R-Iowa, said Thursday that he had been briefed on the supplemental FBI report and concluded "there's nothing in it that we didn't already know."

"The most notable part of this report is what's not in it," said Judiciary Committee ranking member Dianne Feinstein, referring, presumably, to a lack of FBI investigation into Kavanaugh's past drinking.

You should ignore all of this. Truly. Because, if we're being honest, it doesn't really matter what Trump or Grassley or Schumer or me or you think the report says or doesn't say about Kavanaugh and whether he should be on the court. All that matters are the opinions of the five senators -- three Republicans and two Democrats -- who could break either way on Kavanaugh.

Here's a look at each of the undecideds -- and some attempt to crawl into their brains to figure out what is factoring into their decisions. I'm going to start with the trio of Republicans because I think how they vote will tell us a lot about how the two Democrats make up their minds. (We will update this list as we learn more about where each of these senators stand).

The Republicans

1. Susan Collins, R-Maine: Collins is the lynchpin of this whole thing, to my mind. She's emerged over the past five-ish years as the face of the fading group of centrists within the Senate. This has been -- : Collins is the lynchpin of this whole thing, to my mind. She's emerged over the past five-ish years as the face of the fading group of centrists within the Senate. This has been -- as I noted on Wednesday -- a very good thing for her political career.

But this decision could be the toughest one of her 20-plus-year Senate career, and the one with the most potentially serious political implications, too. The anti-Kavanaugh forces have been all over Collins -- protesting outside her office and raising better than $1 million for her eventual 2020 Democratic challenger if she votes for the judge. The senator herself has revealed little of her thinking; at the end of last month, CNN reported that Collins had major concerns about the spate of allegations from women against Kavanaugh.

And remember this; Collins' initial resistance to Kavanaugh was concern over whether he might help make abortion illegal. After meeting with him for more than two hours in August, the Maine Republican emerged to tell reporters that Kavanaugh "said that he agreed with what Justice Roberts said at his nomination hearing, in which he said it was settled law."

Coming out of the reading the FBI report, Collins praised the probe as "a very thorough investigation" -- which suggests she may be leaning in favor of voting for Kavanaugh.

2. Jeff Flake: The retiring Arizona senator is the reason the FBI supplemental investigation happened at all. His : The retiring Arizona senator is the reason the FBI supplemental investigation happened at all. His second thoughts as the vote on Kavanaugh neared in the Senate Judiciary Committee wound up forging a deal whereby the FBI would look into claims made by Ford and Ramirez.

Flake, who has been on a media binge since he delayed the Kavanaugh vote, has made clear that if any of the sexual misconduct allegations against Kavanaugh are true, then he won't be voting for him. Which, duh. Flake has also said that if it can be proven that Kavanaugh didn't tell the truth during his Judiciary Committee testimony that would also disqualify the judge for the nation's highest court.

Presumably, the flip side is also true: If neither corroboration on the sexual assault allegations nor proof that Kavanaugh lied under oath are proved by the FBI report, Flake would, presumably, vote for Kavanaugh.

"We've seen no additional corroborating information," Flake said Thursday, a strong signal that he will be a "yes."

One X-factor: Flake clearly has his eye on the possibility of a third-party presidential bid in 2020, casting himself as a problem-solving Republican fed up with the most Trumpy wing of the party. What better way to show separation than to vote against Trump's SCOTUS pick?

3. Lisa Murkowski: The politics of Murkowski's home state all point to a "yes" vote from her. Alaska went strongly for Trump in 2016 and Murkowski has already had a big brush with the conservative GOP wing in her party in the Last Frontier: She lost the Republican primary in 2010 to a tea party conservative named Joe Miller -- only to win the seat as a write-in candidate in the fall.

That victory, however, appears to have convinced Murkowski that she is more able than the average Republican to buck the wishes and demands of her national party. She has established one of the most centrist voting records in the Senate since that race and seems unafraid of standing up to party leaders when the moment demands it.

All that said, it's hard to imagine Collins and Murkowski going different ways on this vote. And if Collins is leaning in Kavanaugh's favor, then so is Murkowski.

The Democrats

4. Heidi Heitkamp: The North Dakota Democrat : The North Dakota Democrat told WDAY News Thursday that she plans to vote no on Kavanaugh.

Now, when the Republican president wins your state by more than 35 points and then nominates his pick to the Supreme Court, it's probably good politics to vote for Kavanaugh. That goes double for when polling suggests you are behind your Republican challenger with less than five weeks left in the 2018 campaign.

That all comes with one major caveat: It's very hard for me to imagine that Heitkamp (or Manchin) is the 50th vote for Kavanaugh. In other words, no Democrat -- not even a conservative one like Heitkamp -- is going to be the deciding vote that installs a Republican president's pick for the Supreme Court.

Now, if Republicans already have the 50 votes they need, it's hard for me to see Heitkamp voting against Kavanaugh just because.

5. Joe Manchin: Despite West Virginia's very clear Republican lean, Manchin appears to be in pretty strong shape to beat state Attorney General Patrick Morrisey (R) in November.

Given his positioning, lots of Republicans are privately acknowledging that if Manchin votes for Kavanaugh, he's probably sealing his victory in 33 days' time.

That said, like Heitkamp, I can't imagine Manchin being the deciding vote to confirm Kavanaugh. But, if Republicans already have the numbers, why would Manchin vote against Kavanaugh and hand Morrisey a lifeline in a race where he's clearly drowning?

If you look at the various competing interests and beliefs of these five senators, you get a clear sense that Kavanaugh is more likely than not to be confirmed. Things can -- and have -- changed before. But that's the state of play right now.