Sens. Susan Collins, R-Maine, and Joe Manchin, D-W.Va on Friday said they intend to vote in favor of Supreme Court nominee Brett Kavanaugh's confirmation -- two crucial votes that appear to secure Kavanaugh's confirmation to the nation's highest court.

Moments after Collins spoke on the Senate floor announcing her intention to vote for the nominee, Manchin said in a statement he would also vote to confirm Kavanaugh. Manchin said while he had "reservations" due to sexual assault allegations against Kavanaugh and his temperament, he said "I believe he will rule in a manner that is consistent with our Constitution."

Collins said the confirmation had resembled a "caricature of a gutter-level political campaign" and criticized Democrats for announcing their opposition to Kavanaugh before his name was even announced. She also criticized outside groups for distorting Kavanaugh's record and "over-the-top rhetoric."

As she began her speech, she was interrupted by protesters urging her to vote "no." The Senate was flooded by protesters in the days leading up to the vote, with activists hounding Republicans and urging them to vote against Kavanaugh's confirmation, citing decades-old sexual assault allegations against Kavanaugh. Protesters also yelled "shame" at Manchin after his statement.

Collins dismissed claims that Kavanaugh would be a partisan judge, noted he had ruled in favor of parts of ObamaCare and ruled against a Bush-era terror conviction. She also said she was assured that Kavanaugh would not overturn Roe v Wade -- the 1973 decision that found a constitutional right to abortion. She also rejected concerns by Democrats about his temperament and that he was out of the judicial mainstream.

Collins, who told Fox News that she made her decision on Thursday evening, officially made her announcement on the floor of the Senate Friday, hours after the chamber voted 51-49 to advance Kavanaugh's nomination to a final vote on Saturday evening. Collins was one of four key undecided senators who were closely watched for how they would vote. Collins -- along with Sen. Jeff Flake, R-Ariz., and Manchin voted to invoke cloture on the nomination earlier Friday. Sen. Lisa Murkowski, R-Alaska, voted "no."

Flake had suggested he would vote "yes" for Kavanaugh "unless something big changes."

Meanwhile, a source familiar with the confirmation process told Fox News that Manchin called to notify the White House that he was a "yes" for Kavanaugh. But White House officials learned of Collins' decision to support Kavanaugh in real time.

With a 51-49 majority in the Senate, Republicans expect passage by a razor-thin margin. And so every vote has been a subject of intense speculation and scrutiny.

At this point, White House officials are assuming that Sen. Lisa Murkowski, R-Alaska, will remain a "no" during Saturday's confirmation vote. She confirmed that she would not support the nomination in remarks on Capitol Hill Friday evening, saying that, invoking her conscience, "I could not conclude that he is the right person for the court at this time."

She won't vote a straight "no," though. She said that due to the necessary absence of Sen. Steve Daines, R-Mont., they will have a “Pair Between Senators.” This collegial procedure will take place during the Saturday vote and will ensure the vote margin is the same, even with Daines walking his daughter down the aisle at her wedding. Murkowski will ask to be recorded as ‘present’ (though on record as a ‘no’ vote) while Daines is on record as supporting the nomination, but necessarily absent.

Murkowski said it's her hope "that this reminds us we can take very small steps to be gracious with one another."

Kavanaugh’s nomination was embroiled in a deeply divisive controversy that gripped the nation after multiple women made sexual assault allegations originating from his time in high school and college. The most prominent allegation was from California professor Christine Blasey Ford, who said that Kavanaugh assaulted her at a high school party. That allegation resulted in a high-stakes Senate Judiciary hearing last week where both Ford and Kavanaugh testified.

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. The accusations eventually led to President Trump ordering an FBI investigation. Republicans who had seen the FBI’s report said the FBI had produced no credible corroboration of the allegations.

On those accusations, Collins said the Senate would be "ill-served in the long-term if we abandon the presumption of innocence and fairness, as tempting as it may be." She pointed to what she saw as inconsistencies and lack of corroboration in Ford's story and said they fail to meet the "more likely than not" standard. She also said that those trying to defeat Kavanaugh's nomination "cared little if at all" about Ford's well being.

Collins also made reference to allegations by Julie Swetnick that Kavanaugh drugged girls and was present during gang rapes.

"This outlandish allegation was put forth without any credible supporting evidence and simply parroted public statements of others," she said. "That such an allegation can find its way into the Supreme Court process is a stark reminder of why the presumption of innocence is so ingrained in our American conscience."

Protesters clashed with Republican lawmakers in an effort to sway their votes, and initially appeared to have some success. 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. Republicans and conservatives had pushed back, including putting out ads that suggested the fight over accusations against Kavanaugh had implications for men across America.

Senate Majority Leader Mitch McConnell, R-Ky., said early Friday that the vote was "a pivotal day for us here in the Senate."

"The ideals of justice that have served our nation for so long are on display," he said, calling the last two weeks a "disgraceful spectacle."

But Democrats had pointed to not only the sexual assault allegations, which they described but also questions about Kavanaugh’s temperament during the hearing last week and whether he had lied about his drinking during high school and college, and what certain references in his high school yearbook meant. They also sought to paint him as a justice that would swing the court deeply to the right.

Senate Minority Leader Chuck Schumer, D-NY, accused Kavanaugh of being evasive in his answers during his confirmation hearings on key topics. He said his views are “deeply at odds with the progress America has made in the last century of jurisprudence and at odds with what most Americans believe.”

Fox News' Alex Pappas, Chad Pergram, Jason Donner, John Roberts and Mike Emanuel contributed to this report.