President Ronald Reagan's aides and biographers are organizing to challenge factual inaccuracies in Fox News host Bill O'Reilly's new book Killing Reagan: The Violent Assault That Changed a Presidency. O'Reilly is a serial fabricator whose previous books have repeatedly been criticized for inaccuracies.

The Washington Examiner's Paul Bedard reported that O'Reilly's book is “coming under fire from former Reagan aides” and biographers “who are calling it bogus” and “planning a broadside to challenge the book in the coming days.” The individuals reportedly include Reagan biographers Craig Shirley, Steven Hayward, Paul Kengor, Kiron Skinner, and “a handful of former Reagan aides.”

Shirley said that Killing Reagan “is garbage, total B.S.,” while former Reagan national security advisor Richard Allen said the book contains “plagiarism, simplicity and deception.”

The DC-based paper noted that the Reagan critics pointed to O'Reilly's writing about Reagan's mental state and a purported brewing staff mutiny as main objections.

John Heubusch, the executive director of The Ronald Reagan Presidential Foundation and Library, said O'Reilly's book “does a disservice to history.”

In a September interview with Media Matters' Joe Strupp, Ron Reagan called O'Reilly a “snake oil salesman” who doesn't invest “a lot of time or energy in the truth.” The late president's son said he doesn't plan to read O'Reilly's book because he's “not interested in his theories.”

Questions about factual accuracy are nothing new for O'Reilly and his Killing series, which he has co-authored with Martin Dugard. Killing Lincoln contained a series of mistakes and was criticized for factual errors by Lincoln scholars. Several historians and biographers of General George S. Patton objected to O'Reilly's Killing Patton theory that the World War II commander was assassinated by the Soviet Union.

O'Reilly took a major hit earlier this year when his boasts about his reporting career began falling apart under scrutiny. One of those included his claim in Killing Kennedy -- contradicted by numerous pieces of evidence -- that he personally heard the shotgun blast that killed a figure in the investigation into President John F. Kennedy's assassination.