(CNN) President Donald Trump has called Attorney General Jeff Sessions "mentally retarded" and a "dumb Southerner," striking a far more shocking and profane tone in private than his public attacks, according to a new book from legendary journalist Bob Woodward.
Trump's long-simmering anger stems from Sessions' decision to recuse himself from the Russia investigation. Woodward describes how Trump viewed this as a backstabbing betrayal by someone he hoped would shield him from trouble.
The 448-page opus from the Pulitzer Prize-winning author, "Fear: Trump in the White House," is slated for public release on September 11. CNN obtained a copy of the book, which Woodward says is drawn from hundreds of hours of background interviews with dozens of firsthand sources, including people in Trump's inner circle.
Woodward's reporting brings a credibility that distinguishes 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.
The White House on Tuesday accused Woodward of spreading "fabricated stories" but did not deny any of the anecdotes in the book about Sessions.
Here are some of the many revelations from the book about the deteriorating relationship between Trump and Sessions, as reported by Woodward:
Late Tuesday night, Trump denied calling Sessions "mentally retarded" or a "dumb Southerner," and accused Woodward of making it up.
"The already discredited Woodward book, so many lies and phony sources, has me calling Jeff Sessions 'mentally retarded' and 'a dumb southerner,' " Trump tweeted. "I said NEITHER, never used those terms on anyone, including Jeff, and being a southerner is a GREAT thing. He made this up to divide!"
Some Republicans criticized Trump on Tuesday for his comments about Sessions. Georgia Sen. Johnny Isakson said "I resent that," when asked about Trump's mockery of Sessions' southern accent. Wisconsin Sen. Ron Johnson, a fierce Trump ally, said Trump's comments were "totally inappropriate."
Over the past year, Trump has publicly attacked his handpicked attorney general on Twitter and in television interviews -- including a series of blistering tweets last month. Trump previously dubbed Sessions "our beleaguered A.G." and criticized his actions as "very weak" and "disgraceful." But Woodward's book exposes a new level of vitriol.
Sessions took the rare step of firing back at Trump after one of the President's most recent salvos. In a public statement, Sessions defended his control over the Justice Department and said it "will not be improperly influenced by political considerations."
As has happened before, some senior Republicans on Capitol Hill rushed to Sessions' defense and expressed confidence in his performance.
But a few cracks emerged when two key senators opened the door to confirming a new attorney general after the midterms. Trump seemed to embrace that idea in an interview with Bloomberg in late August, when he said Sessions' job was safe until at least November.
In that interview, Trump also repeated his desire for Sessions to investigate his political opponents, including Hillary Clinton, the Democratic presidential nominee in 2016.
UPDATE: This story has been updated to reflect reaction to Woodward's book.