McCabe's book, "The Threat: How the FBI Protects America in the Age of Terror and Trump," was scheduled for release Dec. 4. He now says it will come out in February.
"Having been singled out for irregular unfair treatment over the past year, I am concerned it could be happening again," McCabe said in a statement issued through a spokeswoman.
McCabe, who spent more than 20 years with the FBI, was fired in March for what the Justice Department called a lack of candor as an inspector general report accused him of misleading investigators about his role in a disclosure to the news media. He has denied any wrongdoing.
McCabe has been a repeated target of President Donald Trump's ire. Trump has accused him of having lied during an internal investigation and of being politically biased because of his wife's run for office in Virginia and her acceptance of campaign contributions from the political action committee of a close Hillary Clinton ally.
He has also been at odds with Attorney General Jeff Sessions, who fired him, and with Sessions' deputy, Rod Rosenstein.
The FBI declined to comment Thursday.
FBI policy states that current and former employees who wish to publish FBI information must submit their manuscripts for review to ensure that they are not revealing classified material or anything that could interfere with ongoing investigations or operations.
The FBI says it generally responds to requests for prepublication reviews within 30 days but that more time may be needed for publications that are especially long, sensitive or technical.
The book's publisher, St. Martin's Press, has called the book a candid account of McCabe's career and defense of the FBI's independence.
It has said McCabe will describe "a series of troubling, contradictory, and often bizarre conversations" with Trump and other high officials that led him to believe the "actions of this President and his administration undermine the FBI and the entire intelligence community" and threaten the general public.
The company declined to comment Thursday except to say that the new publication date is Feb. 12.
The book could pull back the curtain on McCabe's own tense relationships with Trump and Rosenstein.
McCabe is known to have kept memos documenting sensitive conversations with both men, including ones that reportedly describe Rosenstein as having floated the idea of secretly recording the president after the firing of FBI Director James Comey and of invoking constitutional procedures to get Trump removed from office. The Justice Department issued a statement from someone who recalled the recording remark being made and said it was meant sarcastically.
McCabe and Rosenstein also had a tense encounter after special counsel Robert Mueller was appointed in which the two each suggested that the other should withdraw, according to a person familiar with the exchange who was not authorized to discuss the private conversation and spoke on condition of anonymity.
McCabe was concerned that Rosenstein, who wrote a memo that preceded Comey's firing, could become a witness in Mueller's investigation while Rosenstein was concerned that McCabe might be conflicted because of his earlier public support for his wife's unsuccessful Democratic campaign for the Virginia state Senate, according to the person. The Washington Post first reported the encounter.
Associated Press writer Hillel Italie in New York contributed to this report.
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