President Donald Trump continued challenging the accuracy of reporter Bob Woodward’s book about his administration on Monday.

“The Woodward book is a Joke,” Trump wrote, questioning damaging stories in the book from anonymous sources. “Many have already come forward to say the quotes by them, like the book, are fiction.”

Trump previewed his own book about his administration.

“Dems can’t stand losing,” he wrote. “I’ll write the real book!”

White House chief of staff Gen. John Kelly, Defense Secretary Gen. Jim Mattis, and former Gov. Chris Christie have all disputed the accuracy of the book.

“What Bob Woodward wrote about me in the book was profoundly wrong and he never picked up the phone to fact check with me … he didn’t do his homework,” Christie said on ABC News on Sunday.

Woodward claims his book includes interviews with hundreds of people in Washington. It also relies heavily on insider knowledge from former staff secretary Rob Porter and former economic adviser Gary Cohn.

The book will be released on September 11:

The Woodward book is a Joke – just another assault against me, in a barrage of assaults, using now disproven unnamed and anonymous sources. Many have already come forward to say the quotes by them, like the book, are fiction. Dems can’t stand losing. I’ll write the real book! — Donald J. Trump (@realDonaldTrump) September 10, 2018