(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.

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