Omarosa Manigault-Newman is about to rip the lid off what she deems the deteriorating mental condition of President Trump in her bombshell new book.

In an exclusive excerpt obtained by DailyMail.com, Omarosa, 44, who first met Trump when she appeared on The Apprentice and later became an assistant to the president, tells of the dread she felt while watching Trump's interview with Lester Holt last May.

'While watching the interview I realized that something real and serious was going on in Donald's brain. His mental decline could not be denied,' she writes in Unhinged: An Insider's Account of the Trump White House.

'Many didn't notice it as keenly as I did because I knew him way back when. They thought Trump was being Trump, off the cuff.

'But I knew something wasn't right.'

In an exclusive excerpt of her new book, Omarosa, who first met Trump when she appeared on The Apprentice and later became the president's Director of African-American Outreach, tells of her dread while watching Trump's interview with Lester Holt last May

'Many didn't notice it as keenly as I did because I knew him way back when. They thought Trump was being Trump, off the cuff,' Omarosa writes. 'But I knew something wasn't right'

Omarosa was beside herself when the president contradicted the White House party line that FBI head James Comey was fired based on the recommendation by the Department of Justice.

'For the Lester Holt interview, I watched it on a small TV in the upper press room (the lower press room was built on top of the old swimming pool and turned into the briefing room) by the press secretary's office,' she writes.

'Throughout this erratic and contradictory interview, I kept thinking, 'Oh no! Oh no! This is bad!

'Donald rambled. He spoke gibberish. He contradicted himself from one sentence to the next.

'Hope [Hicks, then communications director] had gone over the briefing with him a dozen times hitting the key point that he had fired Comey based on the recommendation by the DOJ which the vice president and other surrogates had been reinforcing for days.'

But when questioned by Holt, the president contradicted previous reports about how the senior law-enforcement officer was dispatched from his office.

Omarosa is the latest former Trump aide to land a book deal, DailyMail.com revealed on Wednesday, and it promises to be the juiciest yet.

In the interview Trump called Comey a 'showboat' and revealed he asked Comey whether he was under investigation for alleged ties to Russia.

Trump also told Holt that he asked Comey whether he was under investigation. He said that he spoke to Comey once over dinner and twice by phone.

'I said, 'If it is possible, would you let me know [if] I am under investigation'? He said, 'You are not under investigation.''

The White House had previously claimed that a Justice Department recommendation had spurred the President to oust the FBI chief. Reports in The Wall Street Journal and The Washington Post, described the President's claim that Comey told him he was not under investigation as being false.

Trump also said that he had been planning to fire Comey, apparently contradicting initial reports from the White House that it was a recommendation from Deputy Attorney General Rod Rosenstein that spurred Comey's ouster.

The White House did not respond to a request for comment by DailyMail.com.

Omarosa is the latest former Trump aide to land a book deal, DailyMail.com revealed on and it promises to be the juiciest yet.

The former assistant to the president signed a seven-figure deal with Gallery Books - a division of Simon & Schuster - seven months after her dramatic departure from the White House.

According to the publisher, 'Their relationship has spanned fifteen years—through four television shows, a presidential campaign, and a year by his side in the most chaotic, outrageous White House in history.

'But that relationship has come to a decisive and definitive end, and Omarosa is finally ready to share her side of the story in this explosive, jaw-dropping account.'

Former comms director Hope Hicks had gone over the briefing with the president a dozen times hitting the key point that he had fired Comey based on the recommendation by the DOJ before the Holt interview

Former assistant to the president Omarosa Manigault landed the book deal with Simon & Schuster seven months after her dramatic departure from the White House

Omarosa, who served as director of communications for the Office of Public Liaison, was supposedly fired on December 13, 2017 following reports of an altercation with Chief of Staff John Kelly.

Her controversial termination made headlines after it was reported that security had to carry her out of the White House.

She later denied those claims and insisted she had resigned from her post.

The former Apprentice star then appeared on Good Morning America in an exclusive interview with Michael Strahan where she repeatedly teased that she had a 'story' to tell.

Omarosa served as Trump's assistant and as director of communications for the Office of Public Liaison until her dramatic exit in December 2017

'I have seen things that have made me uncomfortable, that have upset me, that have affected me deeply and emotionally,' she said.

Her dramatic interview, however, did not move GMA anchor Robin Roberts, who believed her appearance was her own shameless plug for a book deal and dismissed her antics with 'Bye, Felicia,' a pop culture catch-phrase.

Omarosa is expected to include some of the stories she shared and the ones she teased to Strahan in the book.

After departing the White House, Omarosa appeared on Celebrity Big Brother where she made headlines for comparing it to a plantation; saying she was 'haunted' by Trump's tweets 'every single day;' and telling house guest Ross Matthews that she didn't think America was in good hands.

'No, it's not gonna be okay,' she said, appearing to tear up.

She ended up being the fifth runner-up on the show, evicted during the show's two-hour finale. But she had created plenty of headlines and melodrama along the way.

Omarosa moved back to Jacksonville, Florida full time, where her husband, Pastor John Newman is based.

He leads The Sanctuary at Mt. Calvary Church in Jacksonville.

Last week, the Wall Street Journal reported that Omarosa has been interviewed by federal investigators in the Trump-Cohen probe.

Omarosa previously worked as an editor for OK! Magazine and now-defunct Reality Weekly - which is owned by American Media Inc - which has been accused of paying off former Playboy model Karen McDougal for her story about her affair with the president.

The WSJ reports that Cohen had handled a dispute between Omarosa and AMI after she sued the company over its coverage of her brother's murder in 2011.