U.S. President Donald Trump’s former aide Omarosa Manigault Newman said she’s willing to cooperate with special counsel Robert Mueller’s Russia investigation and is prepared to handover audio recordings of her time at the White House.

Manigault Newman has released recordings of her time in the Trump administration in the lead up to her tell-all book Unhinged, sparking a public feud between the former The Apprentice contestant and the president.

READ MORE: Donald Trump boosted anti-Obama ‘birther’ movement because he’s black, Omarosa says

In a series of interviews on NBC, Manigault Newman also revealed two audio recordings from her time at the White House, including portions of a recording of her firing by chief of staff John Kelly, which she says occurred in the high-security Situation Room, and a phone call with Trump after she was fired.

WATCH: Omarosa says everything in new book can be verified

0:34 Omarosa says everything in new book can be verified Omarosa says everything in new book can be verified

Manigault Newman says she has more recordings. On Monday, asked on MSNBC’s “Hardball” if Mueller — investigating possible coordination between Trump’s 2016 election campaign and Russia — would be interested in any of them, she said, “If his office calls again, anything they want, I’ll share.”

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READ MORE: Recording reveals Trump’s confusion on Omarosa’s firing

On Tuesday, CBS News released another recording it said was unverified but appeared to be Manigault Newman and several Trump campaign aides in October 2016 discussing the potential fallout from a tape of Trump using a racial epithet during the taping of The Apprentice.

Trump on Monday denied the existence of any such tape, citing the show’s former producer, Mark Burnett. Some of the aides on the latest tape also denied the conversation.

.@MarkBurnettTV called to say that there are NO TAPES of the Apprentice where I used such a terrible and disgusting word as attributed by Wacky and Deranged Omarosa. I don’t have that word in my vocabulary, and never have. She made it up. Look at her MANY recent quotes saying…. — Donald J. Trump (@realDonaldTrump) August 14, 2018

“.@MarkBurnettTV called to say that there are NO TAPES of the Apprentice where I used such a terrible and disgusting word as attributed by Wacky and Deranged Omarosa. I don’t have that word in my vocabulary, and never have. She made it up. Look at her MANY recent quotes saying…” Trump tweeted Monday. “…such wonderful and powerful things about me – a true Champion of Civil Rights – until she got fired. Omarosa had Zero credibility with the Media (they didn’t want interviews) when she worked in the White House. Now that she says bad about me, they will talk to her. Fake News!”

….such wonderful and powerful things about me – a true Champion of Civil Rights – until she got fired. Omarosa had Zero credibility with the Media (they didn’t want interviews) when she worked in the White House. Now that she says bad about me, they will talk to her. Fake News! — Donald J. Trump (@realDonaldTrump) August 14, 2018

In an interview with CBS This Morning, Manigault Newman said what she claims in her book can be verified by audio or a paper trail.

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WATCH: Trump ‘certainly’ hated Obama for his race, Omarosa claims

5:56 Omarosa: Trump ‘certainly’ hated Obama for his race Omarosa: Trump ‘certainly’ hated Obama for his race

“If you see it in quotes, it can be verified, corroborated and is well documented,” Manigault Newman said.

READ MORE: Omarosa says she secretly taped her firing, plays audio

The president fired back at his former The Apprentice contestant on Tuesday, calling her a “crazed, crying lowlife” and “that dog.”

WATCH: Kellyanne Conway won’t comment on Trump calling Omarosa a ‘dog’

0:35 Kellyanne Conway won’t comment on Trump calling Omarosa a ‘dog’ Kellyanne Conway won’t comment on Trump calling Omarosa a ‘dog’

“When you give a crazed, crying lowlife a break, and give her a job at the White House, I guess it just didn’t work out. Good work by General Kelly for quickly firing that dog!” the president tweeted.

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When you give a crazed, crying lowlife a break, and give her a job at the White House, I guess it just didn’t work out. Good work by General Kelly for quickly firing that dog! — Donald J. Trump (@realDonaldTrump) August 14, 2018

On Tuesday afternoon, Manigault Newman confirmed she had been interviewed by Mueller’s team, but did not say when.

Manigault Newman’s tell-all books hits stores Tuesday.

— with a file from the Associated Press