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WASHINGTON, DC - JULY 09:  U.S. Circuit Judge Brett M. Kavanaugh looks on as U.S. President Donald Trump introduces him as his nominee to the United States Supreme Court during an event in the East Room of the White House July 9, 2018 in Washington, DC. Pending confirmation by the U.S. Senate, Judge Kavanaugh would succeed Associate Justice Anthony Kennedy, 81, who is retiring after 30 years of service on the high court.  (Photo by Chip Somodevilla/Getty Images)
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(CNN) —  

Sen. Susan Collins said Saturday that while she believes that Dr. Christine Blasey Ford was sexually assaulted, she does not believe that now-confirmed Supreme Court Justice Brett Kavanaugh did it.

“I do not believe that Brett Kavanaugh was her assailant,” the Maine Republican told CNN’s Dana Bash on “State of the Union” in an interview slated to air on Sunday. “I do believe that she was assaulted. I don’t know by whom. I’m not certain when.”

Ford accused Kavanaugh of sexually assaulting her while the two were in high school, prompting a week’s delay in Kavanaugh’s confirmation to allow the FBI to conduct an investigation into the alleged incident. Kavanaugh has denied all allegations.

Collins reviewed the results of the investigation, which included testimony from 10 different witnesses but not from Ford or Kavanaugh, on Friday. She then voted to advance Kavanaugh’s nomination and has said that she will vote yes on Kavanaugh’ during the full Senate’s confirmation vote on Saturday.

Collins told Bash that while she found Ford’s testimony “heart-wrenching,” the fact that both Ford and Kavanaugh said they were “100 percent certain” of their statements meant that she had to look to the FBI for additional corroborating evidence.

“I found Dr. Ford’s testimony to be heart-wrenching, painful, compelling, and I believe that she believes what she testified to,” Collins said. “But we also had a case where Judge Kavanaugh came forward and said, ‘I’m 100 percent certain that this did not happen,’ so here you have two people who are each 100 percent certain of what they’re saying under pain of perjury. So then I had to look at the other evidence, and was there corroborating evidence, and that’s why I pushed hard for the FBI to do a supplemental background investigation.”

At the White House on Sunday, Trump lauded Collins’ hard work and “impassioned” speech on the Senate floor Friday announcing how she would vote.

“I thought that Susan was incredible yesterday. You could see how hard she worked, how hard she was working. She didn’t stop,” Trump said. “And I know it for a fact because I spoke with her, she didn’t stop. She gave an impassioned, beautiful speech yesterday. And that was from the heart, that was from the heart.”

“I have great respect for Susan Collins, and I always have,” he added.

CNN’s Liz Stark contributed to this report.