President Trump Donald John TrumpUS reimposes UN sanctions on Iran amid increasing tensions Jeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Trump supporters chant 'Fill that seat' at North Carolina rally MORE on Tuesday lashed out at Cliff Sims on the day the former White House staffer's book detailing his time in the administration was released, dismissing him as "low level" and "nothing more than a gofer."

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"A low level staffer that I hardly knew named Cliff Sims wrote yet another boring book based on made up stories and fiction," Trump tweeted.

"He pretended to be an insider when in fact he was nothing more than a gofer. He signed a non-disclosure agreement," he added. "He is a mess!"

A low level staffer that I hardly knew named Cliff Sims wrote yet another boring book based on made up stories and fiction. 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! — Donald J. Trump (@realDonaldTrump) January 29, 2019

The tweet marked the first time Trump has publicly commented on Sims's book. The president did not dispute any specific claims in the book.

Excerpts of the tell-all, "Team of Vipers," have been published in recent days, and Sims on Monday appeared on "Good Morning America" and "The Late Show With Stephen Colbert."

During his roughly 18 months in the Trump administration, Sims served as director of White House message strategy and a special assistant to the president, sitting in on high-level meetings. He left his position last May.

In excerpts released from the book, Sims has described sitting with Trump and creating a list of problematic individuals working in the White House.

In another excerpt, Sims portrayed White House counselor Kellyanne Conway Kellyanne Elizabeth ConwayGeorge and Kellyanne Conway honor Ginsburg Trump carries on with rally, unaware of Ginsburg's death George Conway hits Trump on 9/11 anniversary: 'The greatest threat to the safety and security of Americans' MORE as a "cartoon villain brought to life" who bad-mouthed other staffers to the press.

Sims also wrote that White House senior adviser Stephen Miller derided immigrants and refugees and said he'd be happy if "not a single refugee foot ever again touched American soil."

White House press secretary Sarah Huckabee Sanders on Monday said she'd never heard Miller make such comments.

Michael Glassner, the chief operating officer of the Trump campaign, on Tuesday tweeted that the campaign is preparing to sue Sims over violating a nondisclosure agreement. The campaign took similar action against former staffer Omarosa Manigault Newman Omarosa Onee Manigault NewmanTrump hurls insults at Harris, Ocasio-Cortez and other women Pelosi makes fans as Democrat who gets under Trump's skin The Memo: Impeachment's scars cut deep with Trump, say those who know him MORE upon release of her book last year.

Sims's book is the latest in a string of tell-all books that have been written about the Trump White House. Manigault Newman, veteran journalist Bob Woodward and author Michael Wolff each wrote books that described the administration as a chaotic environment where the president and his advisers disparaged one another on a regular basis.

In each case, the president has lashed out at the author and pushed back against the claims made in the book. Trump called Woodward an "idiot," Manigault Newman a "dog" and described Wolff's work as a "fake book."

Each of those books eventually rose to No. 1 on The New York Times's best-seller list.