President Reagan, left, and Vice President Bush go horseback riding at Camp David, Md., July 1981. (Associated Press)

Annelise Anderson is a research fellow at Stanford University’s Hoover Institution and was an official in the Reagan administration’s Office of Management and Budget; she has co-authored and co-edited a number of books on Ronald Reagan. Given that experience, Anderson scored a gig fact-checking the Bill O’Reilly-Martin Dugard book “Killing Reagan.”

Then she saw the manuscript.

“I thought that their selection of materials was very distorting and very hard to correct,” Anderson said in an interview with the Erik Wemple Blog. As a result, Anderson pulled out of her fact-checking/manuscript reviewing arrangement. She also asked that she not be mentioned in the book’s acknowledgments. No problem there: Fox News host Bill O’Reilly isn’t a big acknowledgments guy to begin with; his thank-you note in “Killing Reagan” measures all of four lines.

Anderson linked up with the “Killing Reagan” project through Christopher Cox, a White House counsel for Reagan and an eventual chairman of the Securities and Exchange Commission. Cox received a request from Dugard for assistance with the Reagan project and connected him with Reagan scholars, including Anderson. The two sides settled on a fee for Anderson’s review of the manuscript, though Anderson won’t say how much.

In May, Anderson received the draft of “Killing Reagan.” “They wanted it back in a week,” says Anderson, citing a time frame that’s consistent with the pace of the “Killing” series, which coughs up a different historical thriller each year. Whether the project features a whole bunch of living witnesses (“Killing Reagan”) or no known living witnesses (“Killing Jesus,” “Killing Lincoln“) the production timeline for these manufactured items is about the same. The short window, combined with what Anderson saw as serious problems with the text, convinced her to pull out. “I felt that not only were there some factual errors, which, of course, there always are . . . but I felt that they had selected materials that portrayed Reagan as debilitated by the assassination attempt and having difficulty throughout his presidency,” says Anderson. That was the “distorting” material, in her opinion.

Reading the manuscript warmed up Anderson for her review of the competed book. Published in National Review shortly after the book’s Sept. 22 release date, Anderson’s take ripped O’Reilly and Dugard for shoddy reporting. One of the themes of the book, writes Anderson, is that Reagan “lets others make important decisions for him (not one example is offered) and is not very bright.” She also bridled at the portrayal of Nancy Reagan as the boss of her husband. “Why O’Reilly and Dugard want to present this distorted ‘witch and wimp’ view of Nancy and the 40th president of the United States is a puzzle to me, especially since an alternative view of the effect of Reagan’s near-death experience is so readily available.”

These and other objections have surfaced under the bylines of Anderson’s Reagan-expert peers. A commentary bylined by four Reagan scholars in The Post — Craig Shirley, Kiron K. Skinner, Paul Kengor and Steven F. Hayward — bashed “Killing Reagan” for asserting that there was “serious consideration” of invoking the 25th Amendment to bump Reagan from office after the March 1981 assassination attempt by John Hinckley Jr. “What’s so remarkable about the 11 days Reagan spent in the hospital recovering from his wounds is that beyond the standard discussion of temporary presidential disability among some of the president’s closest aides, none of these aides or cabinet members attempted to invoke the 25th Amendment or succession laws,” writes the anti-“Killing Reagan” group.

In his Monday night broadcast, O’Reilly blasted the Reagan “guardians” who are trashing his book in print. He said the four scholars’ piece in The Post was “almost comical.” The backlash against “Killing Reagan,” he further charged, came from an interesting place. “This time, it’s not the left attempting to deceive us. It is zealous supporters of Ronald Reagan. Before ‘Killing Reagan’ was even finished, my co-author, Martin Dugard, received calls from former California Gov. Pete Wilson and former [Securities and Exchange Commission Chairman] Christopher Cox warning us — warning us — not to say anything negative about Mr. Reagan. Cox, by the way, is the guy who presided over the mortgage debacle that collapsed the economy in 2007.” Omitted from O’Reilly’s rip was the fact that Dugard was the one who invited Cox into the process, as Cox told the Erik Wemple Blog. Efforts to secure comment from Dugard and from the book’s publisher, Henry Holt, have been unsuccessful.

Cox, too, denies having warned the “Killing Reagan” team against writing negative stuff. “The interests of the Reagan scholars was in accuracy only. There was never any admonition about merely negative things,” said Cox in a chat yesterday with the Erik Wemple Blog.

Even though Anderson didn’t want her name associated with “Killing Reagan,” she says she did some pro bono work in pointing out problems with the manuscript. Some of those suggested changes, she says, were implemented for the final version. However: “The overall thrust of the book remains the same,” she says.