Last week White House Press Secretary Sarah Huckabee Sanders charged the book is "riddled with lies".
Manigualt-Newman told NBC's Chuck Todd she recorded conversations to protect herself in a White House known for throwing people under the bus. But she told Chuck Todd on Sunday that, after the book had closed, she was able to hear a recording of Trump during a trip to Los Angeles. "The false story ... that I tried to charge the residents of the White House, and it's a lie", she said.
"I have documentation, a whole treasure-trove of documentation for everything you see in this book", she said.
She confirmed that Trump never said the N-word in her presence, though she said it was possible he used the racial slur to describe her "because Donald Trump talks about everyone behind their backs".
The truly troubling thing about the tape, as an alarmed Twitter quickly picked up on, is that it exists at all. Asked by TMZ if it's fair to say that the president is "causing tensions among African-Americans right now" after the "LeBron James situation", she replied with a s short sentence: "he wants to start a race war".
Omarosa Manigault Newman campaigns for then-candidate Donald Trump in Charlotte on October 14, 2016.
The casting of Manigault Newman as unstable raises the question of why the Trump administration hired someone like her in the first place.
Her book has come under intense scrutiny with many calling it a tome of falsehoods and uncorroborated gossip.
She recounts how Trump battled to have a tanning bed installed when he moved into the White House.
In the immediate aftermath of last year's march, Trump drew broad criticism when he appeared initially reluctant to condemn the extreme right-wingers - many of whom have rallied behind him since his election, including David Duke, a former KKK leader and avowed racist and anti-Semite who praised Trump's "courage" in defending white nationalist protesters.
And Trump called her a "lowlife" during a photoshoot on Saturday.