An upcoming book about Supreme Court Justice Brett Kavanaugh’s path to the nation’s highest court by a Washington Post editor is under fire for what critics call “really problematic” inaccuracies - and it hasn’t even been released yet.

Washington Post deputy editorial page editor Ruth Marcus’s upcoming book, “Supreme Ambition: Brett Kavanaugh and the Conservative Takeover,” is billed as a behind-the-scenes look at what she calls a “thirty-year mission by conservatives to win a majority on the Supreme Court.”

Washington Post reporter Robert Barnes reported on Thursday that his colleague’s book would claim Supreme Court justice Anthony M. Kennedy asked President Trump to put Kavanaugh on the Supreme Court list. Barnes wrote that, according to Marcus’ book, Justice Kennedy pulled President Trump aside following a 2017 Rose Garden swearing-in ceremony for Justice Neil M. Gorsuch to discuss the next Supreme Court openings and suggested Kavanaugh.

“The justice’s message to the president was as consequential as it was straightforward, and it was a remarkable insertion by a sitting justice into the distinctly presidential act of judge picking,” Marcus wrote, according to Barnes.

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The Post indicated that Kennedy announced his retirement 14 months later, after Kavanaugh’s name was added to Trump’s list of potential successors. According to Barnes, the book claims Kennedy’s son Gregory had informed White House adviser Kellyanne Conway that his father was pleased Trump won the election because he wanted to be succeeded by a Republican – although Gregory Kennedy denied this claim, which is noted by Marcus in a footnote of the book.

“If this is material that appears in Ruth Marcus’s book, and I assume it does since Bob Barnes wrote about it and they know each other, it’s really problematic,” a source close to the confirmation process told Fox News. “A lot of what is said it just not accurate.”

The source, who spoke on the condition of anonymity but was involved in the confirmation process, said Justice Kennedy “never” provided unsolicited guidance about any potential candidate for either the U.S. Supreme Court or the U.S. Court of Appeals.

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“He never went and lobbied the president on any prospective nominee,” the source said. “That’s the gravamen of what Ruth Marcus is saying… that’s not correct and it’s the first glaring inaccuracy. I know this because I was there.”

The source feels Marcus had to come up with “new and exciting” storylines because there have already been multiple books about the Kavanaugh confirmation process, but that isn’t the only theory for the “erroneous” excerpts reported by her Post colleague.

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A second source, who was also involved in the confirmation process, told Fox News that Kennedy simply “is not the kind of guy who would ever proactively offer his views” on a potential replacement.

“He’s a very proper gentleman,” the source said, adding that the claim is “flat-wrong, way off, a big swing and a miss.”

The Washington Post declined a direct comment and pointed Fox News to the book’s publisher, Simon & Schuster.

"I stand behind the reporting in my book,” Marcus told Fox News through a Simon & Schuster spokesperson.

The Post first reported Christine Blasey Ford’s claims that Kavanaugh sexually assaulted her during a Maryland house party in the early 1980s – a claim Kavanaugh has vehemently denied.

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The paper was eventually mocked for a subsequent report that slammed Kavanaugh over purchasing Washington Nationals tickets on his credit card, and also placed a story about Kavanaugh coaching youth basketball under their “Public Safety” section online.

“The Washington Post failed in its efforts to defeat Brett Kavanaugh. They were on a search-and-destroy mission and they failed,” the source said. “What they have to do now to save whatever face they have left, is they have to be able to say, ‘Oh look it was really close, there was angst, there was concern, there was a time when the confirmation might not have actually succeeded,’ because if they can take that narrative then what they did wasn’t completely a failed attempt.”

Carrie Severino co-wrote “Justice on Trial: The Kavanaugh Confirmation and the Future of the Supreme Court,” which hit No. 1 overall on Amazon’s bestseller list following its July release. While researching her book, Severino and co-author Mollie Hemingway spoke with over 100 high-level sources, including Trump himself, Supreme Court justices, dozens of U.S. Senators and senior White House officials but she says none of them ever mentioned the Kennedy claims in Marcus’s book.

“We never heard anything about Justice Kennedy lobbying uninvited for his successor. Neither did our reporting show Leonard Leo being anything but steadfast and unequivocal in support of Justice Kavanaugh,” Severino told Fox News.

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“Anybody who knows Justice Kennedy knows that he would never offer unsolicited advice about who ought to succeed him and anybody who says it is just being ridiculous." — Leonard A. Leo

Federalist Society executive vice president Leonard A. Leo, a member of the transition team to replace Justice Kennedy, advised Trump on selecting both Gorsuch and Kavanaugh in addition to playing a key role in identifying nearly all of Trump’s judicial nominees.

Marcus’s forthcoming book, according to her Washington Post colleague, indicates that Leo wasn’t sold on Kavanaugh and advocated for more conservative candidates. The book also reportedly claims that Leo pushed for an alternative candidate once Christine Blasey Ford claimed Kavanaugh sexually assaulted her.

A source close to Leo disputed this, saying Blasey Ford’s claims against Kavanaugh actually pushed Leo to fight on Kavanaugh’s behalf. The source noted that Leo felt Blasey Ford’s claims were “Clarence Thomas all over again” and it wasn’t a time for indecision or backpedaling. The source said that Leo even defended Kavanaugh in a series of heated phone calls with prominent conservative lawmakers – which contradicts the Post’s claim that Leo advocated finding another candidate.

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“I don’t know where Marcus is getting this story from,” the source told Fox News. “I don’t know who she is getting it from and I don’t know what is causing people to say it.”

Severino said she didn’t hear about the Federalist Society executive seeking an alternate candidate, either.

“There was no so-called 'Plan B.' Everyone understood the stakes and all were fully committed to the confirmation of Brett Kavanaugh the entire time, from the president on down," Severino said.

Leo blasted claims in Marcus’ book when reached by Fox News for comment.

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“Anybody who knows Justice Kennedy knows that he would never offer unsolicited advice about who ought to succeed him and anybody who says it is just being ridiculous,” Leo said. “I’ve had a very longstanding friendship with Brett Kavanaugh, going back to the late 1980s, anyone who knows my friendship with Justice Kavanaugh knows this is simply absurd.”

“Supreme Ambition: Brett Kavanaugh and the Conservative Takeover” is scheduled to hit book stores on December 3.