In her new memoir, "Unhinged," former White House adviser Omarosa Manigault Newman claims President Donald Trump considered getting sworn in for the presidency on his book, "The Art of the Deal."

Though it's not mandatory for presidents to use the Bible for the swearing-in portion of an inauguration ceremony, it has been standard practice throughout US history.

Manigault Newman wrote that she told Trump that although she knew he wouldn't be a "traditional president," the idea was "just too crazy."

Manigault Newman claimed Trump tried to convince her that he was kidding after she shot down the idea.

In her new memoir, "Unhinged," former White House adviser Omarosa Manigault Newman claims President Donald Trump considered getting sworn in for the presidency on his book, "The Art of the Deal."

In the days leading up to his inauguration, Trump allegedly said, "Omarosa, what do you think about me getting sworn in on 'The Art of the Deal?'"

Though it's not mandatory for presidents to use the Bible for the swearing-in portion of an inauguration ceremony, it has been standard practice throughout US history. Manigault Newman questioned Trump as to why he wouldn't continue this trend.

"'The Art of the Deal' is a bestseller! It's the greatest business book of all time," she says Trump told her. "It's how I'm going to make great deals for the country. Just think how many copies I'd sell—maybe commemorative a inauguration copy?!"

Manigault Newman wrote she then told Trump that although she knew he wouldn't be a "traditional president," the idea was "just too crazy." She said she warned Trump not to "repeat that idea to anybody else," claiming the two then laughed and Trump wanted her to believe "he was kidding."

The White House did not immediately respond to Business Insider's request for comment on the anecdote.

White House officials spent the weekend hitting back at discussion of the allegations Manigault Newman makes in her book, with the press secretary Sarah Sanders saying the book is "riddled with lies and false accusations" in a statement released Friday afternoon, Trump calling Manigault Newman Newman a "lowlife " on Saturday, and counselor to the president Kellyanne Conway dismissing the claims on the Sunday political shows.

President Donald Trump was sworn in on two Bibles, including one that was used by President Abraham Lincoln and another that was gifted to Trump by his mother when he was a child. Jim Bourg/Reuters

Manigault Newman said the alleged exchange was revealing in two ways.

First, she claimed it was a reminder that Trump "has no knowledge of the Bible at all," adding, "It might as well be a paper brick to him."

Manigault Newman cited Trump's infamous gaffe about "Two Corinthians" during the 2016 campaign as evidence of his biblical ignorance.

"Since the Bible has little significance to [Trump], it may have felt disingenuous to him to take an oath on it," Manigault Newman wrote. "But 'The Art of the Deal' meant a lot to him. Nothing has more meaning to Donald than himself."

Manigault Newman said this conversation was also revealing in the sense Trump "hadn't fully made the shift from being a salesman" and was still "hardwired to constantly promote Trump brands." She claimed it was natural for Trump to think of the inauguration as a "branding opportunity."

Trump was ultimately sworn in on two Bibles, including one that President Abraham Lincoln used and another that Trump's mother gave him when he was a child.

"Unhinged: An Insider's Account of the Trump White House" comes out on August 14.