The Twitter spat comes as an interview with ABC News' George Stephanopoulos is set to air on Sunday night, in which Comey will discuss details from his new book, "A Higher Loyalty: Truth, Lies and Leadership," which goes on sale Tuesday.
Following several tantrums and attacks coinciding with the release of book excerpts, the president began his Sunday obsessively attacking Comey, the memoir, Bill Clinton and Loretta Lynch. Trump tweets: "It was my great honor to fire him".
Trump and his allies have already launched a counterattack.
Though Democrats and their mainstream media allies have lavished disgraced former FBI Director James Comey with praise for his upcoming gossip book, not everybody feels similarly, including his own former coworkers.
- Many Democrats were livid about Comey after the election.
Royals fall to Angels 5-4 in second game of series
That's impressive enough, but he's done it for a team that has only three wins on the year. You have to keep him on your roster if he can keep this up, even if it's just once a week.
In the book, a copy of which was obtained by POLITICO, Comey, in describing his first meeting with the president in January 2017, wrote, "His face appeared slightly orange, with bright white half-moons under his eyes where I assumed he placed small tanning goggles, and impressively coiffed, bright blond hair, which upon close inspection looked to be all his".
The publicity tour - and the book - will be the first time the American public has heard extensively from Comey since his explosive testimony before the Senate Intelligence Committee in June of past year. "I never asked Comey for Personal Loyalty", Trump wrote. When speaking to then-President-elect Trump and his team about the election scandal, Comey was surprised at how focused they were on the public relations aspect, he said.
Watch the exclusive interview in a special edition of "20/20" on Sunday, April 15 at 10 p.m. ET on ABC.
'I recall Trump listening without interrupting, and asking only one question, which was really more of a statement: "But you found there was no impact on the result, right?"
When the Federal Bureau of Investigation director first informed the president-elect of the salacious, unsubstantiated charges in the Christopher Steele dossier, Trump "strongly denied the allegations, asking - rhetorically, I assumed - whether he seemed like a guy who needed the service of prostitutes". In the clip, Comey characterizes the situation as surreal. "I started to tell him about the allegation was, that he had been involved with prostitutes in a hotel in Moscow in 2013 during a visit for the Miss Universe pageant and that the Russians had filmed the episode". I paused, again. "You will always get honesty from me", I said.
Trump's allies have prepared an extensive campaign to fight back against Comey's publicity tour, trying to undermine his credibility by reviving the blistering Democratic criticism of him before he was sacked almost a year ago. He paused. "That is what I want, honest loyalty", he said.