Supreme Court nominee Brett Kavanaugh will either be headed toward confirmation in the Senate by mid-Friday morning or be faced with yet another hurdle in a process that keeps finding new ways to surprise people.

By late Thursday, Republicans weren't quite sure what three of their own members will do when Majority Leader Mitch McConnell, R-Ky., asks senators to vote to end debate on the embattled nominee on Friday.

Sens. Jeff Flake of Arizona, Susan Collins of Maine, and Lisa Murkowski of Alaska haven't said whether a supplemental FBI report on sexual assault allegations has satisfied them that those claims are without merit, or at least aren't corroborated by other witnesses.

Flake said early Thursday the report contained " no additional corroborating information" about the claims, which many saw as a sign he's on board with the nominee. Later reports said Republicans believed Flake was on board, but he hadn't declared when he might release a clear statement, and he hadn't even tweeted on the subject for more than a week.

Flake has also shown himself to be prone to last-minute changes of heart. Last week, after long talks with his Democratic friend Sen. Chris Coons of Delaware, he said he wouldn't vote for Kavanaugh on the floor until the additional FBI report was complete.

Collins indicated Thursday she would decide by Friday morning, but also offered a hopeful sign for Republicans, saying the FBI report was a "very thorough investigation."

But that sets up the possibility of a last-minute scramble by Republicans Friday morning if there are signs that they don't have two of those three undecided Republicans as "yes" votes. The Senate adjourned with plans to convene at 9:30 a.m. Friday. A vote to end debate on the nomination is scheduled at 10:30 a.m.

With 51 votes in the Senate, Republicans can afford to lose one vote, but not two, which means all eyes will be on the three holdout Republicans.

Republicans are also running out of options for picking up Democratic votes if they're needed.

Sens. Joe Donnelly of Indiana and Heidi Heitkamp of North Dakota both voted for Justice Neil Gorsuch last year, but both have said they are "no" votes on Kavanaugh.

That leaves Sen. Joe Manchin, D-W.Va., as the only Democrat left who could join the Republicans. But if Flake, Collins, and Murkowski all vote "no," even a "yes" vote from Manchin wouldn't be enough.

Even if Republicans coalesce around Kavanaugh by Friday, other signs emerged that the process Sen. Lindsey Graham, R-S.C., has described as "hell" will be upset once more.

Late Thursday, Sen. Steve Daines, R-Mont., said he'd have to return to his home state for the weekend for his daughter's wedding, a commitment that seems likely to upend the GOP's plan to confirm Kavanaugh on Saturday.

The original Republican plan was to vote to end debate on Kavanaugh Friday, then confirm him Saturday. But Daines' news opened the door to holding the vote open all weekend for him, to give him time to return, or to hold the vote Monday.