Hillary Clinton admits in her upcoming book that it was a "mistake" not to publicly deride FBI Director James Comey for saying that she was "extremely careless" for using an unauthorized email server while leading the State Department, all of which led into what Clinton mocked as a "bad joke" that resurfaced later in the 2016 campaign.

"My first instinct was that my campaign should hit back hard and explain to the public that Comey had badly overstepped his bounds — the same argument [Deputy Attorney General] Rod Rosenstein would make months after the election," Clinton writes in What Happened, the Daily Beast reported Wednesday.

"That might have blunted the political damage and made Comey think twice before breaking protocol again a few months later," she continued. "My team raised concerns with that kind of confrontational approach. In the end, we decided it would be better to just let it go and try to move on. Looking back, that was a mistake."

On that same day in the summer of 2016, Comey said his agency would not recommend criminal charges against anyone involved with Hillary Clinton's private email network. He even remarked that "no reasonable prosecutor" would bring charges.

But later that year in October, just before the presidential election, Comey's team found new emails on a computer used by Anthony Weiner, husband to Clinton aide Huma Abedin.

Upon hearing the news, Abedin "burst into tears," Clinton wrote.

She also questioned whether Comey was playing a "bad joke."

"The FBI wasn't the Federal Bureau of IFs or Innuendos. Its job was to find out the facts," she wrote. "What the hell was Comey doing?"

The case was again closed on Nov. 6, but critics, including Clinton, have lamented that there was irreparable damage done to the Democratic candidate's image that swayed some people who cast early votes. Clinton lost the election to President Trump, who has since fired Comey.

Clinton's book is set to go on sale on Tuesday.