Collins, Flake, Murkowski and Manchin were the only lawmakers who didn't reveal until Friday how they would vote on moving the nomination ahead.
And in a statement issued soon after Collins spoke, Manchin explained he was supporting Kavanaugh notwithstanding the "serious accusations" leveled against the judge and lingering questions about Kavanaugh's temperament.
On Friday, the Senate voted 51-49 to move Kavanaugh's Supreme Court nomination to a final vote, which is expected to take place Saturday. "Nevertheless, the four witnesses she named could not corroborate any of the events of that evening gathering where she says the assault occurred, none of the individuals professor Ford says were at the party has any recollection at all of that night".
Sen. Susan Collins of ME, her longtime friend and fellow moderate Republican, spoke on the Senate floor for 45 minutes, explaining her support for Kavanaugh in detail.
Trump weighed in shortly after the result was announced, tweeting, "Very proud of the U.S. Senate for voting "YES" to advance the nomination of Judge Brett Kavanaugh!".
Dianne Feinstein of California, the Judiciary Committee's top Democrat, said Kavanaugh's testimony at last week's dramatic hearing should "worry us all", citing what she called "a hostility and belligerence that is unbecoming" of a Supreme Court nominee.
With just hours before the vote, more than 1,000 protesters, mostly women, broke through barricades and staged a raucous sit-in protest on the US Capitol steps, just feet away from the imposing doors to the Rotunda.
Other Republicans later pushed back against protestors. Sen. As the lone Republican to vote against cloture, it would be very odd for her to then vote for his confirmation. Murkowski said she'd use an obscure procedure that lets one senator offset the absence of another without affecting the outcome. And my heart goes out to anyone who has experienced any type of sexual assault in their life. That's not conclusive evidence of what they will do on Saturday, but it sure looks better for Kavanaugh's chances than if they had voted against ending debate on the nomination.
Collins hasn't opposed any Supreme Court nominee since she was elected to the Senate in 1996.
"Facts matter. Fairness matters", said Senate Majority Leader Mitch McConnell (R-Ky.) "The presumption of innocence is sacrosanct".
Speaking to reporters on Air Force One as he flew to Kansas for a political rally, Trump said he was "very, very, very happy" about the vote and said Kavanaugh will be "a brilliant Supreme Court justice for many years".
Sen. Dianne Feinstein, D-Calif., on the Senate floor before the vote, raised concerns that Kavanaugh would vote to overturn Roe v Wade - the 1973 decision that found a constitutional right to abortion - and was extreme on gun rights. But he added that based on the Federal Bureau of Investigation report, "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".
In a twist, Murkowski said she will state her opposition but vote "present" as a courtesy to Kavanaugh supporter Sen. 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. 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.
As the day began Friday, it remained unclear how Murkowski, Collins, Flake and Manchin would vote on the floor. "I found her testimony to be honest, painful and compelling. It was very hurtful", she said.
Kavanaugh's nomination as a replacement for retiring justice Anthony Kennedy was controversial from the start - but the initial focus was exclusively on the conservative views held by the married father of two. "Do you mind telling me so I can read about him?"