President Trump fired off a fresh barrage of tweets against former FBI Director James Comey on Sunday, continuing his assault on the man he fired ahead of the release of Comey's explosive new memoir. Mr. Trump's early-morning missives slammed the ex-director as a "slimeball," while simultaneously casting Comey as someone he "hardly knew."

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.

In a clip from the ABC interview released on Saturday, Comey said his belief that Hillary Clinton would win the 2016 presidential election was a factor in his decision to disclose the investigation into her use of a private email server as secretary of state.

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Mr. Trump responded on Sunday, criticizing the admission and calling Comey a "slimeball!"

Unbelievably, James Comey states that Polls, where Crooked Hillary was leading, were a factor in the handling (stupidly) of the Clinton Email probe. In other words, he was making decisions based on the fact that he thought she was going to win, and he wanted a job. Slimeball! — Donald J. Trump (@realDonaldTrump) April 15, 2018

The president followed that up with criticism of the director's book, calling it "badly reviewed" and rattling off a litany of his long-standing critiques of the FBI and Justice Department:

The big questions in Comey’s badly reviewed book aren’t answered like, how come he gave up Classified Information (jail), why did he lie to Congress (jail), why did the DNC refuse to give Server to the FBI (why didn’t they TAKE it), why the phony memos, McCabe’s $700,000 & more? — Donald J. Trump (@realDonaldTrump) April 15, 2018

Later, Mr. Trump claimed Comey throws former Attorney General Loretta Lynch "under the bus" in his new book. The president suggested that Lynch's 2016 conversation on a Phoenix airport tarmac with former President Bill Clinton revolved around a promised seat on the Supreme Court in exchange for backing off on any potential charges against Hillary Clinton for her use of a private server. (Lynch and the former president have both vehemently denied anything improper was discussed at the meeting.)

Comey throws AG Lynch “under the bus!” Why can’t we all find out what happened on the tarmac in the back of the plane with Wild Bill and Lynch? Was she promised a Supreme Court seat, or AG, in order to lay off Hillary. No golf and grandkids talk (give us all a break)! — Donald J. Trump (@realDonaldTrump) April 15, 2018

"No golf and grandkids talk (give us all a break)!" Mr. Trump added, in a jab at Lynch and Clinton's claims that Clinton saw the attorney general on the tarmac and boarded her plane to say hello.

Besides taking a break to tweet on the U.S. coalition air strike in Syria, saying his call back to a Bush-era phrase "mission accomplished" should be "brought back," the president disputed ever asking Comey for a loyalty pledge, despite Comey testifying before Congress that he did in fact ask for such an oath during a private dinner at the White House.

I never asked Comey for Personal Loyalty. I hardly even knew this guy. Just another of his many lies. His “memos” are self serving and FAKE! — Donald J. Trump (@realDonaldTrump) April 15, 2018

Slippery James Comey, a man who always ends up badly and out of whack (he is not smart!), will go down as the WORST FBI Director in history, by far! — Donald J. Trump (@realDonaldTrump) April 15, 2018

Mr. Trump delivered a final jab at Comey, criticizing his intelligence and saying he will "go down as the WORST FBI Director in history, by far."