WASHINGTON — Sen. Susan Collins, who had been the last undecided Republican vote on Supreme Court nominee Brett Kavanaugh, announced Friday she will vote in favor of President Donald Trump's pick, virtually ensuring his confirmation when the full Senate holds its final vote on Saturday.

In a speech on the Senate floor that lasted more than 40 minutes, Collins, of Maine, forcefully outlined her belief that Kavanaugh was well-qualified, that the Senate confirmation process "is not a trial" and that she cannot abandon the "presumption of innocence."

It now appears that there will be 51 votes in favor of Kavanaugh, because Democratic Sen. Joe Manchin of West Virginia came out minutes after her speech in favor of the nominee, the only Senate Democrat to back Trump's pick.

"Outstanding!" was the reaction of one White House official to Collins' speech, and White House press secretary Sarah Sanders weighed in on Twitter.

Thank you @SenatorCollins for standing by your convictions and doing the right thing to confirm Judge Kavanaugh. — Sarah Sanders (@PressSec) October 5, 2018

In her remarks, Collins said "fairness" dictates that claims of sexual assault "should at least meet a threshold of 'more likely than not,'" but that the facts presented in the allegations made by Dr. Christine Blasey Ford "lead me to conclude that the allegations fail to meet the 'more likely than not' standard."

"Therefore, I do not believe that these charges can fairly prevent Judge Kavanaugh from serving on the court," Collins said.

"We must always remember that it is when passions are most inflamed that fairness is most in jeopardy," she continued. "The presumption of innocence is relevant to the advice and consent function when an accusation departs from a nominee’s otherwise exemplary record. I worry that departing from this presumption could lead to a lack of public faith in the judiciary and would be hugely damaging to the confirmation process moving forward."

Collins also praised Kavanaugh accuser Ford for her courage and the senator said she believed her when she testified she was sexually assaulted, but she added that she was troubled by the lack of corroborating witnesses for Ford's claim.

"I found her testimony to be sincere, painful and compelling. I believe that she is a survivor of a sexual assault and that this trauma has upended her life," the Maine Republican said. "Nevertheless, the four witnesses she named could not corroborate any of the events."

She said she disagreed with those saying that "unless Judge Kavanaugh's nomination is rejected, the Senate is somehow condoning sexual assault."

"Nothing could be further from the truth," she said.

"The MeToo movement is real," Collins added. "It matters. It is needed and it is long overdue," she said.

Earlier, Collins said Kavanaugh had received "rave reviews" for his 12 years as a federal judge, including regarding his "judicial temperament" and that he was "more a centrist that some of his critics maintain."

She finished her remarks by saying, "I will vote to confirm Judge Kavanaugh."

Protesters chanting, "Vote no, show up for Maine women!" interrupted Collins at the beginning of her remarks on the Senate floor, but she continued on after they were escorted from the Senate gallery.

Three female GOP senators — Joni Ernst of Iowa, Shelley Moore Capito of West Virginia, and Cindy Hyde Smith of Mississippi — sat behind Collins as she spoke.

Meanwhile, Manchin released his statement saying he would vote for Kavanaugh moments after Collins finished speaking.

"Based on all of the information I have available to me, including the recently completed FBI 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," said Manchin, who is facing a tough reelection battle in a state won in a huge landslide in 2016. "I do hope that Judge Kavanaugh will not allow the partisan nature this process took to follow him onto the court."

Only one Republican, Sen. Lisa Murkowski of Alaska, is expected to vote against Kavanaugh on Saturday.

Friday morning, a small handful of lawmakers — Collins, Manchin, Murkowski, and Sen. Jeff Flake, R-Ariz. — had been considered potential swing votes on Kavanaugh.

But Flake, who earlier voted "yes" to advance Kavanaugh's nomination in key procedural motion, told reporters that he planned to vote to confirm Kavanaugh on Saturday unless something big changes.

Murkowski, however, voted against the procedural motion to move forward. Later, she indicated that she would stick to her decision to vote "no" on Kavanaugh on Saturday. She told reporters Friday that it was "truly the most difficult evaluation of a decision that I've ever had to make."

"I have been wrestling with whether or not this was about the qualifications of a good man or is this bigger than the nominee. And I believe we are dealing with issues right now that are bigger than a nominee," Murkowski said. "I believe that Brett Kavanaugh is a good man, I believe that he is a good man, it just may be that in my view, he's not the right man for the court at this time."