'He spoke gibberish': Omarosa claims Trump's 'mental decline' was so obvious it 'could not be denied'
Omarosa Manigault during an interview with ABC News (Screenshot)

Explosive allegations from former White House official Omarosa Manigault-Newman are beginning to emerge in the press ahead of her upcoming tell-all book release.

"Unhinged: An Insider's Account of the Trump White House" will go on sale August 14, but the DailyMail has received excerpts from the book.

One section makes the claim that President Donald Trump is experiencing noticable cognitive decline.

"While watching the [Lester Holt] interview I realized that something real and serious was going on in Donald's brain. His mental decline could not be denied," Omarosa writes. "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."

"Donald rambled. He spoke gibberish. He contradicted himself from one sentence to the next," she elaborated.

According to the book's publisher, Omarosa has known Trump for 15 years but completely severed ties with him following her alleged firing from the White House.