Former FBI Director James Comey James Brien ComeyDemocrats fear Russia interference could spoil bid to retake Senate Book: FBI sex crimes investigator helped trigger October 2016 public probe of Clinton emails Trump jabs at FBI director over testimony on Russia, antifa MORE's unreleased book has risen to the No. 2 spot on Amazon's list of best-sellers.

"A Higher Loyalty: Truth, Lies, and Leadership," which is scheduled to be released on April 17, has seen a surge in preorders.

The book had been No. 15 on the list on Saturday morning, CNN reported, but jumped in the rankings by Sunday morning.

Within hours of the initial publication of this story, the book shot to the number one spot on Amazon's best-seller list.

Comey is expected to use his upcoming book tour to directly rebut President Trump Donald John TrumpBiden leads Trump by 36 points nationally among Latinos: poll Trump dismisses climate change role in fires, says Newsom needs to manage forest better Jimmy Kimmel hits Trump for rallies while hosting Emmy Awards MORE's attacks on the FBI.

Trump has taken to Twitter in recent days to attack Comey following the firing of FBI Deputy Director Andrew McCabe Andrew George McCabeGraham: Comey to testify about FBI's Russia probe, Mueller declined invitation Barr criticizes DOJ in speech declaring all agency power 'is invested in the attorney general' GOP votes to authorize subpoenas, depositions in Obama-era probe MORE.

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On Saturday, Trump tweeted that the "Fake News" was "beside themselves that McCabe was caught, called out and fired."

"How many hundreds of thousands of dollars was given to wife’s campaign by Crooked H friend, Terry M, who was also under investigation?" he tweeted, referring to Hillary Clinton Hillary Diane Rodham ClintonBiden leads Trump by 36 points nationally among Latinos: poll Democratic super PAC to hit Trump in battleground states over coronavirus deaths Battle lines drawn on precedent in Supreme Court fight MORE and former Virginia Gov. Terry McAuliffe (D).

"How many lies? How many leaks? Comey knew it all, and much more!"

On Sunday, Trump again took to Twitter to go after Comey, accusing him of lying under oath.

“Wow, watch Comey lie under oath to [Sen. Chuck Grassley Charles (Chuck) Ernest GrassleyGOP set to release controversial Biden report McConnell locks down key GOP votes in Supreme Court fight Senate Republicans face tough decision on replacing Ginsburg MORE (R-Iowa)] when asked ‘have you ever been an anonymous source...or known someone else to be an anonymous source...?’ ” Trump tweeted.

"He said strongly 'never, no.' He lied."

Trump also referred to the former FBI director as "lying James Comey" in a subsequent tweet.

Comey, who was fired by Trump last year, on Saturday posted a tweet directed at the president, saying the American people will "hear my story very soon."

"And they can judge for themselves who is honorable and who is not,” Comey tweeted.

Updated at 4:27 p.m.