One veteran lawyer who recently represented President Donald Trump believes he is a "liar" and told Trump he could end up in "an orange jump suit" if he testifies before special counsel Robert Mueller, according to a new book from legendary journalist Bob Woodward.

The 448-page opus from the Pulitzer Prize-winning investigative reporter, "Fear: Trump in the White House," goes behind the scenes of the Russia investigation . The book, based on confidential background interviews, portrays a President even more deeply obsessed with the Mueller investigation than has been previously reported or understood.

Woodward reveals confidential conversations between Trump and his attorney John Dowd, who led the President's legal team until March. Readers get a glimpse into the world of the notoriously tight-lipped Mueller and, for the first time, get a window into his negotiations with Trump's lawyers.

Woodward describes how Dowd made Trump sit for a mock interview to try to prove to the President that testifying would be a terrible idea. Trump failed the test miserably, Woodward writes, and Dowd left convinced that the President could not survive Mueller's questioning without committing perjury. Dowd believed Trump was incapable of telling the truth.

In a shocking twist, Trump's lawyers later took a dramatic step and re-enacted the scene in front of Mueller. Dowd played the role of special counsel and posed questions to Jay Sekulow, who impersonated a combative Trump. Sekulow is still one of Trump's personal lawyers.

Dowd eventually advised Trump, "Don't testify. It's either that or an orange jump suit." Woodward reports that Dowd couldn't bring himself to tell Trump directly what he believed was true: "You're a fucking liar."

In a statement Tuesday, Dowd denied some of the key anecdotes and quotes attributed to him in the book. He criticized Woodward for fueling an "endless cycle of accusations and misrepresentation."

"I do not intend to address every inaccurate statement attributed to me -- but I do want to make this clear: there was no so-called 'practice session' or 're-enactment' of a mock interview at the Special Counsel's office," Dowd said. "Further, I did not refer to the President as a "liar" and did not say that he was likely to end up in an 'orange jump suit'. It was a great honor and distinct privilege to serve President Trump."

CNN obtained a copy of the book, which is set for public release September 11. Woodward's book relies on hundreds of hours of taped background interviews and dozens of sources in Trump's inner circle, as well as documents, files, diaries and memos, including a note handwritten by Trump himself.

Woodward's reporting comes with a credibility that separates this book from previous efforts on Trump. The author and Washington Post journalist has won two Pulitzer Prizes, including one for his coverage of the Watergate scandal that led to President Richard Nixon's resignation.

Trump did not grant an interview for the book, despite repeated requests from Woodward. In the past, Trump has been complimentary about Woodward and praised his work . The White House said in a statement Tuesday that the book is full of "fabricated stories, many from former disgruntled employees."

Trump fails practice Mueller interview

Taking readers inside the White House residence, Woodward describes how Dowd captured Trump's attention one afternoon in January 2018 for a "practice session" of a sit-down interview with Mueller.

"If the questions seem harmless, don't treat them that way," Woodward recounts Dowd telling Trump, guiding his client. "... just answer the question. Okay? Got it"

The dry run turned into a disaster in Dowd's eyes.

Trump answered many of the questions with "I don't know" or "I don't remember." Woodward reports that when Dowd asked Trump about his decision to fire FBI Director James Comey, Trump launched into an unstoppable verbal assault. He cursed and repeated unsubstantiated attacks about Comey, similar to the ones he posts on Twitter, calling him a "crook" and a "liar."

Dowd worried if the real interview played out this way, Trump would fire Mueller on the spot. Woodward writes that Dowd "saw the full nightmare" and felt Trump acted like an "aggrieved Shakespearean king."

Trump seemed surprised by Dowd's reaction and asked, "You think I was struggling?"

Dowd re-enacts Trump's performance for Mueller

The book takes readers inside Mueller's office, as Trump's legal team makes the case that there is no need to question the President -- and that any interview would become a perjury trap.

As CNN has reported, Mueller raised the stakes in March, threatening a subpoena for Trump's testimony. Woodward reports that Dowd blew up, saying, "You go right the fuck ahead and get it."

The respected attorney then grabbed Mueller's attention with a dramatic move, re-enacting Trump's mock interview. Dowd played Mueller, posing questions to Sekulow, who performed "a perfect Trump," Woodward writes, filled with contradictions, unfounded claims and anger. Dowd said in a statement Tuesday that this did not happen.

Woodward highlights the incredible series of negotiations with Mueller's own words.

"I need the President's testimony," Mueller said, unconvinced by Dowd's arguments to the contrary. "What was his intent on Comey? I want to see if there was corrupt intent."

Despite glowing public praise for the President from Dowd and Sekulow, the book reveals how they privately had no confidence in his ability to tell the truth or size up the threat posed by testifying. Woodward reports Dowd told Mueller that Trump would mess things up after just three questions.

With that in mind, Dowd offered an unorthodox proposal: Mueller could slip into the White House, put Trump under oath and Trump would read from a "script" prepared by his lawyers.

But Mueller's team swiftly rejected this idea. Woodward writes, "No way. It was unheard of."

Trump: 'I'll be a real good witness'

Dowd repeatedly warned Trump that any interview would surely result in a perjury trap. In one meeting, the President appeared to agree, telling Dowd, "I'm with you. I don't really want to testify." But over time, Trump kept opening the door with his lawyers and in public comments.

Trump argued: "What are people going to say? How is it going to look in the press?" He later added, "I think the President of the United States cannot be seen taking the Fifth."

Time and again, Trump tried to sway Dowd that he was ready to take on Mueller. Dowd bluntly replied, "There's no way you can get through these. ... I wish I could persuade you."

"I'm a good witness. I'll be a real good witness," Trump told his lawyer, almost promising to behave. But Woodward writes that Dowd, who would resign soon afterward, "knew this was self-delusion, total bullshit."