By Denis Slattery

New York Daily News

President Donald Trump’s top aides believe he’s an “idiot” with the understanding of a “fifth or sixth grader” and have gone to great lengths to avert disaster as they struggle with the commander in chief’s impulsive and dangerous personality, according to a new book by legendary journalist Bob Woodward.

The veteran Washington Post journalist paints a damning portrait of a West Wing dominated by a man whose closest advisers go out of their way to circumvent the commander in chief —going so far as to ignore orders, hide information and even swipe papers from his desk.

White House chief of staff John Kelly called Trump “unhinged” and an “idiot,” according to Woodward. Defense Secretary James Mattis describes the president as having the understanding of “a fifth- or sixth-grader.”

Trump’s former personal lawyer John Dowd describes the President as “a f—-ing 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. “I don’t even know why any of us are here. This is the worst job I’ve ever had.”

On Tuesday, the White House brushed off the book as a work of fiction.

“This book is nothing more than fabricated stories, many by former disgruntled employees, told to make the president look bad,” an official said.

Kelly also refuted the claims made about his comments.

“The idea I ever called the president an idiot is not true,” he said.

Following a chemical weapons attack on Syrian civilians in April 2017, Trump reportedly told military brass he wanted to assassinate Syrian President Bashar Assad.

“Let’s f—-ing kill him! Let’s go in. Let’s kill the f—-ing lot of them,” Trump told Mattis.

Mattis responded by telling the president he would begin working on plans, but then hung up the phone and told an aide, “We’re not going to do any of that. We’re going to be much more measured,” according to Woodward.

Woodward, 75, offers an unprecedented look at the inner workings of the Trump administration and top officials’ efforts to deal with a president who has little understanding of world affairs or how government works in the 448-page book, “Fear: Trump in the White House,” which is due out next week and was obtained Tuesday by The Washington Post.

Woodward, a Pulitzer prize-winning journalist known for his reporting on the Nixon-era Watergate scandal, based his account of the current administration on “hundreds of hours of interviews with firsthand sources, meeting notes, personal diaries, files and documents.”

The book describes “an administrative coup d’etat” and a “nervous breakdown” within the executive branch, as senior aides sought to keep information from the president.

Gary Cohn, Trump’s former top economic adviser, twice removed papers from the president’s desk to prevent him from signing documents that would have led to the U.S. withdrawing from trade deals, including a notification letter pulling out of the North American Free Trade Agreement, Woodward writes.

“I can stop this. I’ll just take the paper off his desk,” Cohn told former staff secretary Rob Porter.

Trump, who has made no attempt to hide his feelings about Mueller’s Russia investigation, has also struggled privately with the investigation, according to Woodward.

The president’s former attorney, John Dowd, was convinced that Trump would commit perjury if he talked to the special counsel and staged a practice session to make his point.

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

But Trump was surprised. “You think I was struggling?” he asked.

The book goes on to describe Trump’s paranoia about the Russia probe as all-consuming, with the president telling aides that “everybody’s trying to get me,” following Mueller’s appointment, according to the tome.

Woodward writes that Trump often explodes on top aides and erupts in bursts of profanity when talking about people he is displeased with.

“This guy is mentally retarded,” Trump said of Attorney General Jeff Sessions. “He’s this dumb southerner,” Trump reportedly told Porter, mocking Sessions by feigning a southern accent.

Former chief of staff Reince Priebus was described by the president as being “like a little rat. He just scurries around.”

Woodward’s work will be the latest in a string of books that have offered often damning insight into the inner workings of the Trump White House. In January, author Michael Wolff’s book, “Fire and Fury,” was filled with wild claims about Trump’s behavior since taking office.

Former Trump adviser Omarosa Manigault Newman released her own tell-all, titled “Unhinged,” which detailed what she described as the president’s mental decline over the past decade.