Transcript for Sen. Lisa Murkowski breaks with GOP, votes 'no' on Kavanaugh

We begin on the eve of what looks to be a vote tomorrow that will send judge Brett Kavanaugh to the supreme court. Today, high drama playing out on the senate floor. Undecided senators revealing their intentions, including Republican Susan Collins of Maine, now voting yes to confirm. Shame on you! Protesters there all day, packing the hallways. Shouting down the Democrat who will vote yet, Joe Manchin. It appears president trump's nominee will be confirmed. Mary Bruce with the story. Reporter: With the fate of judge Kavanaugh hanging in the balance, the day began with key senators still undecided. With just one hour to go before the crucial vote, Democrat Joe Manchin racing back to that secure room to review the FBI investigation into Kavanaugh's alleged sexual misconduct. For Manchin and the three undecided Republicans, Susan Collins, Jeff flake, and Lisa murkowski, the pressure is monumental. Many women live in fear. How do you think Kavanaugh will make us feel? When it comes time to vote, Collins is a yes. So is Joe Manchin. Senator Jeff flake, also a yes. But Lisa murkowski votes no, the only Republican to break with her party. Later swarmed by reporters, she explains her decision. I did not come to a decision on this until walking into the floor this morning. I believe that Brett Kavanaugh is a good man. It just may be that in my view, he's not the right man for the court at this time. Reporter: Leaving the capitol, flake, who demanded the FBI do its investigation, makes clear he stands with Kavanaugh. Do you plan to vote yes tomorrow? Unless something big changed, I don't see what would, but anyway, I'm glad we had a better process. Reporter: What about Susan Collins? Her office all day flooded with protesters. She takes to the senate floor. Vote no! Vote no! Reporter: For 45 minutes, she meticulously outlines Kavanaugh's judicial record, insisting he is more of a centrist than his critics contend. Collins is pro-choice, and she says in one-on-one meetings Kavanaugh convinced her he would respect the precedent of roe V. Wade. When I asked him, would it be sufficient to overturn a long established precedent if five current justices believed that it was wrongly decided, he emphatically said no. Reporter: And when she gets to the allegations of sexual misconduct, Collins declares the FBI investigation did not corroborate the accusations of Christine blasey Ford. The presumption of innocence and fairness do bear on my thinking and I cannot abandon them. In evaluating any given claim of misconduct, we will be ill served in the long run if we abandon the presumption of innocence and fairness, tempting though it may be. Reporter: Then, her final decision. I will vote to confirm judge Kavanaugh. Thank you, Mr. President. Reporter: Moments later, Manchin says he too is a yes. Ensuring judge Kavanaugh will be confirmed. Do you believe Dr. Ford? I believe Dr. Ford. Reporter: But Manchin is soon drowned out. Shame on you! Reporter: And chased out. Another dizzying day on capitol hill. Mary, the math very clear, the vote tomorrow. Brett Kavanaugh, likely to be confirmed. I know you will be there tomorrow. But you spoke with lawyers for Dr. Christine blasey Ford. Reporter: Her lawyers tell me this is a grave injustice, but she has no regrets. As for what comes next, Ford plans to return to teaching, and hopefully spend time with her family. David? The vote looking likely for tomorrow evening.

This transcript has been automatically generated and may not be 100% accurate.