President Trump on Tuesday lashed out at an ex-White House aide who published a tell-all book about the infighting and leaking among those who work for the president, claiming Cliff Sims was a “low level staffer” he barely knew.

“A low level staffer that I hardly knew named Cliff Sims wrote yet another boring book based on made up stories and fiction,” the president tweeted. “He pretended to be an insider when in fact he was nothing more than a gofer. He signed a non-disclosure agreement. He is a mess!”

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Sims’ book, “Team of Vipers: My 500 Extraordinary Days in the Trump White House,” was released on Tuesday and includes numerous photographs of Sims with the president, as well as descriptions of instances where Sims had one-on-one time with him.

A former Trump campaign communications adviser, Sims, 34, went on to serve as special assistant to the president and director of White House message strategy before leaving the post last year.

Michael Glassner, the chief operation officer of the Trump campaign, tweeted that the campaign planned to sue Sims, accusing him of violating a non-disclosure agreement.

“The Trump campaign is preparing to file suit against Cliff Sims for violating our NDA,” Glassner tweeted.

Sims did not immediately return a request for comment from Fox News. But he tweeted photos of himself with the president after Trump's comments.

In an appearance on ABC’s "Good Morning America" on Monday, Sims pushed back against the notion he didn't have much access to Trump.

“Well the good news is the people who buy the book, you’ll see an insert in the middle that has just dozens of photographs of us in private settings, in the private dining room, and walking down the west colonnade… not a lot of aides have that kind one-on-one access to the president,” Sims said.

The book takes particular aim at Trump adviser Kellyanne Conway, referring to her as “a cartoon villain brought to life” and accusing her of leaking to reporters.

“Her agenda — which was her survival over all others, including the president — became more and more transparent,” Sims writes in the book. “Once you figured that out, everything about her seemed so calculated; every statement, even a seemingly innocuous one, seemed poll-tested by a focus group that existed inside her mind.”

Conway fired back in a statement to Vanity Fair.

"The real leakers, past and present, get much more positive press than I do. While it’s rare, I prefer to knife people from the front, so they see it coming," Conway said.

According to the book’s description, “Sims stood with the president in the eye of the storm raging around him, and now he tells the story that no one else has written — because no one else could. The story of what it was really like in the West Wing as a member of the president’s team. The story of power and palace intrigue, backstabbing and bold victories, as well as painful moral compromises, occasionally with yourself.”

It added: “And he took notes. Hundreds of pages of notes. In real-time.”