WASHINGTON — Bob Woodward isn't a "left-wing hack." He didn't deceive or betray anyone to get access to the White House. And while his methods have drawn scrutiny and criticism in the past, his reporting on power has been the gold standard ever since he and Carl Bernstein broke Watergate.

That's why his new book "Fear" appears, ironically, to have struck such fear in the heart of its subject, President Donald Trump. Of all the government and media institutions and players Trump has attacked since he first launched his campaign for the presidency in 2015, Woodward could be the toughest to discredit. There's even a Trump tweet for that.

Only the Obama WH can get away with attacking Bob Woodward. — Donald J. Trump (@realDonaldTrump) March 1, 2013

"There's a war on truth by him," Woodward said on the "Today" show Monday morning, adding that the president's former lawyer, John Dowd, concluded Trump shouldn't testify in special counsel Robert Mueller's Russia probe "because he can't tell the truth."

Disregarding his own observation, Trump has launched a sustained attack on Woodward and the book, which hits stores Tuesday.

It "is a total fraud," Trump said on Air Force One last week. "The book that was written was fiction. I don't speak that way. I'm highly educated and always did well."

There's reason for Trump to worry.

"This detailed account shows a president whose own advisers are desperate to protect the American people from the chaos he creates, and makes it clear that the biggest obstacle facing the president’s agenda is often the president himself,” said Michael Steel, who was an aide to then-House Speaker John Boehner, R-Ohio. Steel worked extensively with Woodward when the author was reporting for "The Price of Politics," a book about President Barack Obama's dealings with Congress.

White House press secretary Sarah Sanders said Monday that on-the-record pushback on Woodward from administration officials should be given more weight than the accounts of unnamed figures used by Woodward.

"Those are far more credible sources," she said.

While there will be a tendency in Washington to treat the book as a warmed-over reiteration of long-understood dynamics within the administration — Trump's top lieutenants see him as both an "idiot" and a danger to the country — the book is powerful both for giving a unique Woodward credence to the narratives of authors Omarosa Manigault-Newman and Michael Wolff and for new nuggets that could turn off Trump voters, particularly those who sided with him but are not part of his solid bloc of about 35 percent of voters.

What will Southerners, adherents of "rule of law" Republicanism and families of people with disabilities make of Woodward's report that Trump mocked Attorney General Jeff Sessions' Alabama accent and called the nation's top law enforcement official "mentally retarded" and a "dumb Southerner?"

Trump denied it on Twitter.

"Never used those terms on anyone, including Jeff, and being a southerner is a GREAT thing," Trump wrote.

But Trump's disdain for Sessions, so often articulated in his own Twitter feed, is as legendary as Woodward's ability to get everyone to talk. And Trump has called people "mentally retarded" before. With that context, it isn't hard to believe he called Sessions a "dumb Southerner," too.

What will the populists make of Woodward's report that Ivanka Trump, denying her official role as a White House aide, told Steve Bannon that she was above staff work?

"I'm not a staffer! I’ll never be a staffer," the younger Trump fumed. "I’m the first daughter."

There likely won't be a moment when Trump's base turns against him. His base is rock-solid, and it has stuck with him through calamities that would have destroyed any other politician.

But for Trump to win in 2020, and for Republicans to hang onto both houses of Congress in November, a lot of voters who are neither part of his base nor viscerally repulsed by him will have to decide whether they want him to gain or lose power.

Woodward's detail about Trump's handling of policy — the fear he created at the Pentagon and among top Cabinet officials with his itches to upend American relationships abroad, for example — is at once less sexy than name-calling, whether he's the target or the launcher of personal invective, and more important to the question of whether he ought to be checked or even defeated at the ballot box.

In a New York Times op-ed, an anonymous senior White House official wrote that "the dilemma — which he does not fully grasp — is that many of the senior officials in his own administration are working diligently from within to frustrate parts of his agenda and his worst inclinations."

Sen. Lindsey Graham, R-S.C., who has become a Trump ally, pointed to Woodward's credibility on that front Thursday, even as he said some of the book should be taken with a grain of salt.

"The whole theme of the book is that President Trump can run hot and be volatile," Graham said. "I agree."

Even denials from White House chief of staff John Kelly and Defense Secretary Jim Mattis, based on specific passages in the book, felt rote. Kelly denied saying the president is an "idiot" and Mattis said he'd never heard anyone in his orbit — including himself — use "contemptuous" language about the president.

It's not unusual for Washington figures to deny reporting that is true if it is politically disadvantageous to them, even if they are the source — "happens frequently," Woodward said on "Today." NBC News reported on Kelly calling Trump an "idiot" in May. It would be unsustainable for him to continue in his job as chief of staff if he didn't deny using that term to describe the president.

But neither he nor Mattis dared to launch a real counterattack on Woodward, who records most of his interviews. Both of them commented in written statements, rather than rushing to cameras to defend their honor or the president's.

Typically, that wouldn't be a huge problem for a president who has been able to cast past books and news reports as the work of people with axes to grind, money to make or simply a bias against him.

But Woodward? He's wealthy enough that he doesn't need another best-seller to sustain himself. He didn't turn his back on Trump like Manigault-Newman or blend into the background of a new White House staff like Wolf. And he's detailed the good, the bad and the ugly of presidential decision-making without regard for the party or political agenda of the commander in chief since before many White House aides were born.

"Woodward has always had his detractors, but there’s no question that he is relentless in his research and incredibly effective in getting people — lots of people — to talk, and in great detail," Jeff Shesol, a speechwriter in the Clinton White House and an author of political nonfiction books. "Everything I’ve read about [the new book] suggests that he has once again put together a mosaic of multiple impressions and recollections that add up to an indisputable truth: in this case, that Trump is utterly, disgracefully, dangerously unfit for the job he’s got."

If there's a credibility gap, Woodward is usually on the right side of it. That's according to Trump — or, at least the 2013 Trump.