Former Democratic presidential nominee Hillary ClintonHillary Diane Rodham ClintonGrassley blasts Democrats over unwillingness to probe Clinton GOP lawmakers cite new allegations of political bias in FBI Top intel Dem: Trump Jr. refused to answer questions about Trump Tower discussions with father MORE says she was "dumbfounded" when she learned then-FBI Director James Comey was renewing the investigation into her private email server just days before the election.

"I was just dumbfounded. I thought, what is he doing? The investigation was closed. I know there's no new information. I'd certainly given everything of any relevance to them," Clinton said on NBC's "Today" on Wednesday. 

"Then it became clear, this was not necessary, he could have called me up, he could've called others involved and said 'Hey, can we look at this new stuff and make sure its stuff we've seen before?' Absolutely. Have at it," she continued. 

"But no, he had to write letters to Congress, of which immediately were leaked. So I feel very strongly that he went way beyond his role in doing what he did," she said. 

Clinton also said Comey's intervention played a major role in the outcome of the election. 

"I think the determining factor was the intervention by Comey on Oct. 28," she said. 

"It stopped my momentum, it drove voters from me — understandably. This is not about the voters, who were saying, 'Well, wait what does this mean and how do I evaluate it?' And so I think that in terms of my personal defeat was the most important factor," she said. 

Clinton's comments come a day after the launch of her new book recounting her experience during the 2016 presidential race, "What Happened." 

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