In an excerpt obtained by DailyMail.com, she cites her former boss' interview with NBC News' Lester Holt previous year as a moment when she presumed "something wasn't right".
In her book, Manigault-Newman writes that "throughout this erratic and contradictory interview, I kept thinking, 'Oh no!"
According to the Daily Mail's excerpt, Hope Hicks, who was then White House communications director, had prepped Trump for the interview and emphasized repeatedly that he was supposed to say that he had fired Comey based on the recommendation by the Department of Justice.
During the interview, Mr Trump sensationally contradicted his own White House's public rationale for the sacking. "His mental decline could not be denied", she wrote.
However, in the interview, Trump went rogue and admitted he fired Comey over the Russian Federation investigation.
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Seven months after she was terminated from her duties at the White House, on December 13, 2017, the memorable personality from The Apprentice will finally tell the story she teased in her exclusive post-White House interview with Michael Strahan on Good Morning America.
"And in fact when I chose to do it, I said to myself, I said you know, this Russian Federation thing with Trump and Russian Federation is a made-up story". In fact, she thinks it's rapidly declining. We also know what campaign staffers told us two years ago and I know the unsafe, blustering bigot on the stage last night is more boorish and less connected to reality than he was ten years ago. Oh no! This is bad!' Donald rambled.
Omarosa Manigault-Newman and the current president of the United States have known one another for many years. "He contradicted himself from one sentence to the next", she elaborated.
She denied the claim and said she had resigned.
Trump could now face potential obstruction of justice charges if the special counsel determines he fired Comey to end the investigation into his campaign's ties to Russian Federation. "He said, 'You are not under investigation, '" the president recalled.