Omarosa Manigault (L) who was a contestant on the first season of Donald Trump's 'The Apprentice' and is now an ordained minister, appears alongside Republican presidential hopeful Donald Trump during a press conference November 30, 2015 that followed Trump's meeting with African-American religious leaders in New York.

"Anything they want, I will certainly cooperate," she said during the "Hardball" interview Monday night.

The president's tweet came the morning after Manigault Newman told MSNBC's Chris Matthews she would cooperate with Robert Mueller if she is contacted again, seemingly confirming that she has been in touch with the special counsel's office. Mueller's team is investigating potential ties between the Trump campaign and the Kremlin, as well as Russian attacks on the 2016 election.

"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," Trump tweeted. "Good work by General Kelly for quickly firing that dog!"

President Donald Trump resumed his Twitter onslaught against former senior White House advisor and "Apprentice" contestant Omarosa Manigault Newman, calling her a "dog" in his most vicious attack yet on his former protege.

The special counsel's office declined to comment.

Manigault Newman recorded several conversations during her nearly one-year stint at the White House. She has already played some for the media, including a recording of chief of staff John Kelly firing her and one of Trump himself expressing dismay over her dismissal.

In a recording Manigault Newman released to NBC, Trump said he didn't know she had been fired, and "I don't love you leaving at all."

Manigault Newman, who was paid as much as then-chief of staff Reince Priebus and other top White House officials during 2017, wrote a tell-all book, "Unhinged: An Insider's Account of the Trump White House." It went on sale Tuesday. The frenzy over the book's contents, which have been disputed by the White House and several observers, has escalated in recent days.

The former White House aide claims in her book that she spoke to investigators earlier this year and "received a call" from the FBI. She has also said in interviews that she heard tapes of Trump saying the n-word, which were recorded during the filming of "Apprentice" episodes.

Trump denied that he used the racial slur. "I don't have that word in my vocabulary, and never have," he tweeted Monday night. He also said that "Apprentice" producer Mark Burnett called to tell him that there were "NO TAPES" of him using the word.

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The White House did not immediately respond to a request for comment.