April 13 (UPI) -- A week ahead of the release of former FBI Director James Comey's memoir, President Donald Trump on Friday launched an attack at the onetime bureau chief -- calling him a "liar" and a "slime ball."
In his book, A Higher Loyalty: Truth, Lies and Leadership, Comey gives a largely unfavorable assessment of the president -- comparing him to a mob boss and calling him "unethical" and "untethered to truth and institutional values."
"James Comey is a proven LEAKER & LIAR," Trump's tweet said. "Virtually everyone in Washington thought he should be fired for the terrible job he did-until he was, in fact, fired. He leaked CLASSIFIED information, for which he should be prosecuted. He lied to Congress under OATH. He is weak."
Trump called his May 2017 firing of Comey "a great honor."
Comey drew upon his experience combating organized crime to describe Trump in his book, and wrote of similarities between the president and mob bosses.
"The boss in complete control. The loyalty oaths. The us-versus-them worldview. The lying about all things, large and small, in service to some code of loyalty that put the organization above morality and above the truth," the book states.
James Comey is a proven LEAKER & LIAR. Virtually everyone in Washington thought he should be fired for the terrible job he did-until he was, in fact, fired. He leaked CLASSIFIED information, for which he should be prosecuted. He lied to Congress under OATH. He is a weak and.....— Donald J. Trump (@realDonaldTrump) April 13, 2018
....untruthful slime ball who was, as time has proven, a terrible Director of the FBI. His handling of the Crooked Hillary Clinton case, and the events surrounding it, will go down as one of the worst "botch jobs" of history. It was my great honor to fire James Comey!— Donald J. Trump (@realDonaldTrump) April 13, 2018
Comey stopped short of accusing Trump of criminal wrongdoing. Special Counsel Robert Mueller is investigating Trump's 2016 campaign team for possible collusion with Russian efforts to influence the presidential race.
"I have one perspective on the behavior I saw, which while disturbing and violating basic norms of ethical leadership, may fall short of being illegal," Comey wrote in the 304-page book.
Comey also wrote that as president-elect, Trump asked him to investigate allegations from a dossier to "prove that it didn't happen" -- referring to a 35-page report compiled by former British intelligence officer Christopher Steele that includes salacious, and unproven, allegations against the president -- including an alleged interaction with prostitutes in Moscow in 2013.
Comey said during a private dinner with Trump in January 2017, Trump asked him to prove the incident didn't happen to ensure first lady Melania Trump didn't believe even "1 percent" of the claims.
"'I remember thinking, 'How could your wife think there's a 1 percent chance you were with prostitutes peeing on each other in Moscow?' I'm a flawed human being, but there is literally zero chance that my wife would think that was true," Comey told ABC News in an inteview that will air Sunday.
"So, what kind of marriage to what kind of man does your wife think [that] there's only a 99 percent chance you didn't do that?"
Due to pre-orders, Comey's memoir is already a best-seller.