It would be a cruel irony if Manchin voted for Kavanaugh and helped save his nomination while a Republican, Murkowski, voted against him, but given that he is up for reelection in a state where Trump remains popular, it is a distinct possibility.
Republicans have a 51-49 majority in the Senate and this razor-thin majority has carried the vote forward, despite two swing votes. They said he'd push the court farther right, including possible sympathetic rulings for Trump.
They urged Senators not to confirm the nomination of Kavanaugh given sexual assault allegations against him.
Brett Kavanaugh denies the claims.
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.
Flake joins fellow Arizona Republican Sen. Patty Murray, D-Wash., said Saturday.
They converged on Capitol Hill and held a rally outside the Supreme Court, chanting: "Kavanaugh has got to go!" "We believe survivors", they yelled.
Meanwhile hundreds of people protested outside the US Capitol against Kavanaugh.
Republicans control the Senate by a meager 51-49. Like so many Americans, I am deeply disappointed in Senator Collins' vote for Kavanaugh. It would be the closest roll call to confirm a justice since 1881, when Stanley Matthews was approved by 24-23, according to Senate records.
The outcome, telegraphed Friday when the final undeclared senators revealed their views, was devoid of the shocks that had come nearly daily since Christine Blasey Ford said last month that an inebriated Kavanaugh tried to rape her at a 1982 high school get-together. Though, when asked how sure she was that Kavanaugh was the boy who attacked her, Dr. Ford said "100%".
Senators on both sides know they have work to do to put the chamber back together again after a ferocious debate that saw them arguing over the sordid details of high school drinking games, sexual allegations and cryptic yearbook entries.
But the fight was defined by the sexual assault accusations. "I have found Judge Kavanaugh to be a qualified jurist who will follow the Constitution and determine cases based on the legal findings before him", he said. Lisa Murkowski announced that she was a definite "no" vote on President Donald Trump's nominee.
Grassley then returned to the Senate floor, where a few minutes later Collins - with three Republican women sitting behind her - delivered a 44-minute speech outlining her support for Kavanaugh, the critical moment that has likely ensured his confirmation in a final vote Saturday. Murkowski had already announced her intention to vote "no". Steve Daines, who supports the nominee but will be at his daughter's wedding in Montana.
"This allows the vote to occur with the same margin as would have occurred without the absence", Stewart added in in an email, which had the subject line "procedural nerd stuff". Flake later said he intends to vote "yes", "unless something big changes". In another example, again following a long period of hemming and hawing, Collins voted to confirm torture mastermind Gina Haspel to lead the Central Intelligence Agency. That previous vote was to limit debate, meaning Kavanaugh's nomination will get a vote probably Saturday.
Manchin was the only Democrat to vote for Kavanaugh's confirmation. They said he also seemed ready to rule for Trump if federal authorities probing his 2016 campaign's connections to Russian Federation try to pursue him in court.