Washington (CNN) President Donald Trump on Tuesday evening amped up his attacks on veteran journalist Bob Woodward, baselessly suggesting he is a Democratic operative because his new book portrays chaos and dysfunction inside the White House.

The tweet comes after CNN and The Washington Post reported on some of the book's most explosive allegations, including disparaging comments Defense Secretary Jim Mattis and White House chief of staff John Kelly privately made about Trump and military actions the President sought to take against Syria and North Korea. Following statements of denial from Kelly, Mattis and others in the book, Trump suggested there was political motivation behind the timing of the book's release.

"The Woodward book has already been refuted and discredited by General (Secretary of Defense) James Mattis and General (Chief of Staff) John Kelly," Trump wrote. "Their quotes were made up frauds, a con on the public. Likewise other stories and quotes. Woodward is a Dem operative? Notice timing?"

The Woodward book has already been refuted and discredited by General (Secretary of Defense) James Mattis and General (Chief of Staff) John Kelly. Their quotes were made up frauds, a con on the public. Likewise other stories and quotes. Woodward is a Dem operative? Notice timing?

Late Tuesday night, Trump denied a specific portion of the book about Attorney General Jeff Sessions. Woodward reported Trump called Sessions "mentally retarded" and a "dumb Southerner."

"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!"

The already discredited Woodward book, so many lies and phony sources, has me calling Jeff Sessions "mentally retarded" and "a dumb southerner." 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!

Woodward, however, said he stood by his reporting in a statement obtained by CNN's Jamie Gangel.

Trump had earlier offered pushback on Tuesday in an interview with the conservative publication Daily Caller

"It's just another bad book. He's had a lot of credibility problems," Trump said of Woodward, who has reported on multiple presidents and alongside Carl Bernstein broke news of the Watergate scandal that ultimately led to President Richard Nixon's resignation.

"It's just nasty stuff," Trump said.

Trump on Tuesday also lamented the fact that he did not sit for an interview with Woodward before publication. Woodward sought through multiple White House officials and others close to Trump to secure an interview with him, to no avail.

Woodward's 448-page book, "Fear: Trump in the White House," 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. It describes how Trump's closest aides have taken extraordinary measures in the White House to try to stop what they saw as his most dangerous impulses, going so far as to swipe and hide papers from his desk so he wouldn't sign them.

Trump called the allegation that officials removed paperwork from his desk to prevent him from signing it "false" and "made up."

Trump's comments Tuesday followed a pair of statements the White House released generally panning the book.

White House press secretary Sarah Sanders called it "nothing more than fabricated stories, many by former disgruntled employees, told to make the President look bad."

White House chief of staff John Kelly also rejected Woodward's reporting that he called Trump an "idiot," even though multiple outlets have also reported that Kelly has privately disparaged the President.

"The idea I ever called the President an idiot is not true," Kelly said in a statement hours after the report was released. Kelly added that he and the President "have an incredibly candid and strong relationship" and that "he and I both know this story is total BS."

"This is another pathetic attempt to smear people close to President Trump and distract from the administration's many successes," Kelly said.

Mattis also denied the quotes attributed to him in Woodward's book.

"The contemptuous words about the President attributed to me in Woodward's book were never uttered by me or in my presence. While I generally enjoy reading fiction, this is a uniquely Washington brand of literature, and his anonymous sources do not lend credibility," Mattis said.

"In serving in this administration, the idea that I would show contempt for the elected commander in chief, President Trump, or tolerate disrespect to the office of the President from within our Department of Defense, is a product of someone's rich imagination," he added.

Trump's former personal lawyer John Dowd also pushed back against allegations against him, including that he described the President as "a f---ing liar" and that he told Trump he would end up in an "orange jump suit" if he testified to special counsel Robert Mueller.

Dowd said he would not address every "inaccurate statement" attributed to him but did deny that he had called Trump a liar or that he would end up in an orange jumpsuit.

Woodward's reporting is drawn from hundreds of hours of interviews with people with firsthand knowledge of the events he describes and quotes he includes are backed up by documentation he reviewed.

"When I have attributed exact quotations, thoughts or conclusions to the participants, that information comes from the person, a colleague with direct knowledge, or from meeting notes, personal diaries, files and government or personal documents," Woodward wrote in a note to readers included in the book.