Woodward's 448-page book, "Fear: Trump in the White House," provides an unprecedented inside-the-room look through the eyes of the President's inner circle. From the Oval Office to the Situation Room to the White House residence, Woodward uses confidential background interviews to illustrate how some of the President's top advisers view him as a danger to national security and have sought to circumvent the commander in chief.

Many of the feuds and daily clashes have been well documented, but the picture painted by Trump's confidants, senior staff and Cabinet officials reveal that many of them see an even more alarming situation — worse than previously known or understood. Woodward offers a devastating portrait of a dysfunctional Trump White House, detailing how senior aides — both current and former Trump administration officials — grew exasperated with the President and increasingly worried about his erratic behavior, ignorance and penchant for lying.

Chief of staff John Kelly describes Trump as an "idiot" and "unhinged," Woodward reports. Defense Secretary James Mattis describes Trump as having the understanding of "a fifth or sixth grader." And Trump's former personal lawyer John Dowd describes the President as "a fucking liar," telling Trump he would end up in an "orange jump suit" if he testified to special counsel Robert Mueller.

"He's an idiot. It's pointless to try to convince him of anything. He's gone off the rails. We're in crazytown," Kelly is quoted as saying at a staff meeting in his office. "I don't even know why any of us are here. This is the worst job I've ever had."

CNN obtained a copy of Woodward's book, scheduled for release September 11. The explosive revelations about Trump from those closest to him are likely to play into the November midterm election battle. The book also has stunning new details about Trump's obsession with the Russia probe, describing for the first time confidential conversations between the President's lawyers and Mueller. It recounts a dramatic session in the White House residence in which Trump failed a mock Mueller interview with his lawyers.

In separate statements Tuesday afternoon, Kelly denied that he called Trump an "idiot," Dowd denied using the "orange jump suit" phrase and Mattis said the quotes attributed to him were "a product of someone's rich imagination."

The White House accused Woodward of spreading "fabricated stories" about Trump.

"This book is nothing more than fabricated stories, many by former disgruntled employees, told to make the President look bad," White House press secretary Sarah Sanders said. "While it is not always pretty, and rare that the press actually covers it, President Trump has broken through the bureaucratic process to deliver unprecedented successes for the American people. Sometimes it is unconventional, but he always gets results."

Woodward, however, said he stood by his reporting in a statement obtained by CNN.

He sums up the state of the Trump White House by writing that Trump was an "emotionally overwrought, mercurial and unpredictable leader." Woodward writes that the staff's decision to circumvent the President was "a nervous breakdown of the executive power of the most powerful country in the world."

Circumventing the President

The book opens with a dramatic scene. Former chief economic adviser Gary Cohn saw a draft letter he considered dangerous to national security on the Oval Office desk.

The letter would have withdrawn the US from a critical trade agreement with South Korea. Trump's aides feared the fallout could jeopardize a top-secret national security program: the ability to detect a North Korean missile launch within just seven seconds.

Woodward reports Cohn was "appalled" that Trump might sign the letter. "I stole it off his desk," Cohn told an associate. "I wouldn't let him see it. He's never going to see that document. Got to protect the country."

Cohn was not alone. Former staff secretary Rob Porter worked with Cohn and used the same tactic on multiple occasions, Woodward writes. In addition to literally stealing or hiding documents from Trump's desk, they sought to stall and delay decisions or distract Trump from orders they thought would endanger national security.

"A third of my job was trying to react to some of the really dangerous ideas that he had and try to give him reasons to believe that maybe they weren't such good ideas," said Porter, who as staff secretary handled the flow of presidential papers until he quit amid domestic violence allegations. He and others acted with the acquiescence of former chief of staff Reince Priebus, Woodward reports.

Woodward describes repeated attempts to bypass Trump as "no less than an administrative coup d'état."

The Russia obsession

Woodward's book relies on hundreds of hours of taped 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 explains that he talked with sources on "deep background," meaning he could use all the information but not say who provided it.

His reporting comes with the credibility of a long and storied history 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.

In one revelatory anecdote, Woodward describes a scene in the White House residence. Trump's lawyer, convinced the President would perjure himself, put Trump through a test — a practice interview for the one he might have with Mueller. Trump failed, according to Dowd, but the President still insisted he should testify.

Woodward writes that Dowd saw the "full nightmare" of a potential Mueller interview, and felt Trump acted like an "aggrieved Shakespearean king."

But Trump seemed surprised at Dowd's reaction, Woodward writes. "You think I was struggling?" Trump asked.

Then, in an even more remarkable move, Dowd and Trump's current personal attorney Jay Sekulow went to Mueller's office and re-enacted the mock interview. Their goal: to argue that Trump couldn't possibly testify because he was incapable of telling the truth.

"He just made something up. That's his nature," Dowd said to Mueller.

The passage is an unprecedented glimpse behind the scenes of Mueller's secretive operation — for the first time, Mueller's conversations with Trump's lawyers are captured.

"I need the president's testimony," Mueller said. "What was his intent on Comey? ... I want to see if there was corrupt intent."

Despite Dowd's efforts, Trump continued to insist he could testify. "I think the President of the United States cannot be seen taking the fifth," Trump said.

Dowd's argument was stark: "There's no way you can get through these. ... Don't testify. It's either that or an orange jump suit."

What he couldn't say to Trump, according to Woodward, was what Dowd believed to be 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."

Trump's insults and humiliation

Throughout the book, Woodward portrays the President as a man obsessed with his standing in the media and with his core supporters. Trump appears to be lonely and increasingly paranoid, often watching hours of television in the White House residence. "They're out to get me," Trump said of Mueller's team.

Trump's closest advisers described him erupting in rage and profanity, and he seemed to enjoy humiliating others.

"This guy is mentally retarded," Trump said of Sessions. "He's this dumb southerner," Trump told Porter, mocking Sessions by feigning a southern accent.

Trump said that Priebus is "like a little rat. He just scurries around."

And Trump demeaned former New York Mayor Rudy Giuliani to his face, when Giuliani was the only campaign surrogate willing to defend then-candidate Trump on television after the "Access Hollywood" tape, a bombshell video where Trump described sexually assaulting women.

"Rudy, you're a baby," Trump told the man who is now his attorney. "I've never seen a worse defense of me in my life. They took your diaper off right there. You're like a little baby that needed to be changed. When are you going to be a man?"

Trump's predecessors are not spared either. In a conversation with Sen. Lindsey Graham, Trump called President Barack Obama a "weak dick" for not acting in Syria, Woodward reports.

National security concerns

Woodward's book takes readers inside top-secret meetings. On July 27, 2017, Trump's national security leaders convened a gathering at "The Tank" in the Pentagon. The goal: an intervention to try to educate the President on the importance of allies and diplomacy.

Trump's philosophy on diplomacy was personal. "This is all about leader versus leader. Man versus man. Me versus Kim," he said of North Korea.

His inner circle was worried about "The Big Problem," Woodward writes: Trump's lack of understanding that his crusade to impose tariffs could endanger global security.

But the meeting didn't go as planned.

Trump went off on his generals. "You should be killing guys. You don't need a strategy to kill people," Trump said of Afghanistan.

He questioned the wisdom of keeping US troops in South Korea.

"So Mr. President," Cohn said to Trump, "what would you need in the region to sleep well at night?"

"I wouldn't need a fucking thing," the President said. "And I'd sleep like a baby."

After Trump left the Tank, Secretary of State Rex Tillerson declared: "He's a fucking moron."

The book provides the context for the now-infamous quote that marked the beginning of the end for Tillerson's tenure. Tillerson tried to downplay the dispute -- "I'm not going to deal with petty stuff like that," he said at a news conference after NBC reported the remark — but he was ultimately fired via tweet.

Woodward also quotes an unnamed White House official who gave an even more dire assessment of the meeting: "It seems clear that many of the president's senior advisers, especially those in the national security realm, are extremely concerned with his erratic nature, his relative ignorance, his inability to learn, as well as what they consider his dangerous views."

A recurrent theme in Woodward's book is Trump's seeming disregard for national security concerns because of his obsession with money — trade deficits and the cost of troops overseas.

In meeting after meeting, Trump questions why the US has to pay for such a large troop presence in South Korea.

"We're doing this in order to prevent World War III," Mattis, the defense secretary, bluntly explained to Trump at one January 2018 meeting, which prompted Mattis to tell close associates afterward that Trump had the understanding of a "fifth or sixth grader."

Trump still wasn't convinced. "I think we could be so rich if we weren't stupid," he later said in the meeting, arguing the US was being played as "suckers," Woodward reports.

The 'Ernest Hemingway' of Twitter

Trump's tweets — and his infatuation with Twitter — are a theme throughout the book.

Woodward reveals that Trump ordered printouts of his tweets and studied them to find out which ones were most popular. "The most effective tweets were often the most shocking," Woodward writes.

Twitter was a source of great consternation for national security leaders, who feared — and warned Trump — "Twitter could get us into a war."

Appalled by some of his more outrageous posts, Trump's aides tried to form a Twitter "committee" to vet the President's tweets, but they failed to stop their boss.

Priebus, who was blindsided when Trump announced his firing on Twitter, referred to the presidential bedroom as "the devil's workshop" and called the early morning hours and Sunday night — a time of many news-breaking tweets — "the witching hour."

Trump, however, saw himself as a Twitter wordsmith.

"It's a good thing," Trump said when Twitter expanded its character count to 280, "but it's a bit of a shame because I was the Ernest Hemingway of 140 characters."

'A zoo without walls'

Finally, "Fear" is filled with slights, insults and takedowns from both family and staff that speak to the chaos, infighting and drama that Trump allows to fester around him.

Both Jared Kushner and Ivanka Trump are targeted by the inner circle.

There is a pointed shot at Ivanka from the President's now-ostracized chief strategist Steve Bannon, who frequently clashed with the first daughter and her husband.

"You're nothing but a fucking staffer!" Bannon screamed at Ivanka at a staff meeting, according to Woodward. "You walk around this place and act like you're in charge, and you're not. You're on staff!"

"I'm not a staffer!" she shouted back. "I'll never be a staffer. I'm the first daughter" — she really used the title, Woodward writes — "and I'm never going to be a staffer!"

Two of the harshest comments in the book are directed at Trump and come from his chiefs of staff.

After Trump's Charlottesville, Virginia, controversy , in which he failed to condemn white supremacists, Cohn tried to resign but was instead dressed down by Trump and accused of "treason."

Kelly, who is Trump's current chief of staff, told Cohn afterward, according to notes Cohn made of the exchange: "If that was me, I would have taken that resignation letter and shoved it up his ass six different times."

And Priebus, Trump's first chief of staff, encapsulated the White House and the thrust of Woodward's book by describing the administration as a place with "natural predators at the table."

"When you put a snake and a rat and a falcon and a rabbit and a shark and a seal in a zoo without walls," Priebus is quoted as saying, "things start getting nasty and bloody."

UPDATE: This story has been updated to reflect Mattis' and the White House's responses to Woodward's book, as well as Woodward's defense of his reporting.