Former Democratic presidential nominee Hillary ClintonHillary Diane Rodham ClintonWoman behind pro-Trump Facebook page denies being influenced by Russians Trump: CNN, MSNBC 'got scammed' into covering Russian-organized rally Pennsylvania Democrats set to win big with new district map 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." 

While the former nominee says she takes responsibility for her shocking loss to President Trump in the book, she openly questions the actions of various characters such as Comey, her former primary rival Sen. Bernie SandersBernard (Bernie) SandersDems ponder gender politics of 2020 nominee 2020 Dem contenders travel to key primary states After Florida school shooting, vows for change but no clear path forward MORE (I-Vt.), former President Barack ObamaBarack Hussein ObamaOvernight Energy: Dems ask Pruitt to justify first-class travel | Obama EPA chief says reg rollback won't stand | Ex-adviser expects Trump to eventually rejoin Paris accord Overnight Regulation: Trump to take steps to ban bump stocks | Trump eases rules on insurance sold outside of ObamaCare | FCC to officially rescind net neutrality Thursday | Obama EPA chief: Reg rollback won't stand Ex-US ambassador: Mueller is the one who is tough on Russia MORE and former Vice President Joe BidenJoseph (Joe) Robinette BidenDems ponder gender politics of 2020 nominee Trump: Why didn't Obama 'do something about Russian meddling?' 2020 Dem contenders travel to key primary states MORE.