Recorded evidence exists of President Donald Trump using a racial slur on the set of his NBC reality TV show, according to the authors of a new book -- and it wouldn't be too difficult to obtain.

Allen Salkin and Aaron Short, authors of the new book "The Method to the Madness," told MSNBC's "Morning Joe" that a producer from "The Apprentice" told them on the record that Trump used a racial slur in reference to a black contestant in the show's first season.

"If you're talking about racism today, if you want final, audible evidence that Trump is a racist," Salkin said, "you can ask Bill Pruitt, who was named in our book, an 'Apprentice' producer, who says on the record that Trump used the N-word backstage on a tape that you could probably get to explain his hiring decision on the first season of 'The Apprentice.'"

Pruitt's recollection matches claims made by former "Apprentice" contestant Omarosa Manigault, who also served as a White House adviser.

"On this phone conversation, I was told exactly what Donald Trump said -- yes, the N-word and others in a classic Trump-goes-nuclear rant -- and when he'd said them," said Manigault, who said she has heard the recording. "During production he was miked, and there is definitely an audio track."

Salkin said the contestant Trump referred to with the slur could probably get that tape by suing the show's executive producer, Mark Burnett.

"If Kwame Jackson, the candidate who was not hired, were to file a lawsuit perhaps in discovery against Mark Burnett, MGM and maybe NBC, he could force MGM to open that archive and we could know for sure if there was a tape," Salkin said. "Sam Nunberg, who was Trump's close adviser, like I said 114 on-the-record sources in the book, says if such a tape were to emerge it would change the outcome of the 2020 election."