Edward Klein was in his 11th year as editor of the New York Times Magazine when on two consecutive weeks in July 1987 the prestigious Sunday supplement was cited in editors’ notes for lapses in editorial judgment. During Klein’s tenure the magazine had some notable successes, such as winning a Pulitzer Prize, but it also suffered other high-profile missteps, including publication of a fabricated tale about Khmer Rouge guerrillas in Cambodia.

By October 1987, Klein had departed from the newspaper, and thus began his journey from influential editor to conservative author of bestsellers about powerful figures: the Kennedys, Katie Couric, Hillary Rodham Clinton and, most recently, President Obama. The evolution of his career has raised eyebrows among liberals and conservatives, and the highly personal portraits he crafts have prompted questions about sourcing, accuracy and intent.

His latest, “The Amateur,” in which he contends that the president is ill-suited by experience and temperament to occupy the White House, contains scenes that did not occur or that were vastly misconstrued, according to those who Klein says were present. The Obama book, released by conservative publisher Regnery, has been largely ignored by the mainstream media. Nonetheless, it has sold vigorously thanks in large part to an early boost from conservative blogger Matt Drudge. It will perch at No. 1 on the New York Times bestseller list Sunday for the fourth consecutive week. In the month since its mid-May release, nearly 66,000 copies have been sold, according to Nielsen BookScan.

A pugilist in print, Klein in person is a well-mannered, fit-looking 75-year-old who chooses his words carefully and yields little when challenged. He sat recently for a 21 / 2-hour interview in his Park Avenue apartment, interrupted only by his white-uniformed maid delivering coffee and water on a silver tray.

“If there’s criticism of my work that’s legitimate,” he said, “I’m ready to hear of it.”

Klein is no stranger to criticism. The uproar over his 2005 book about Clinton, “The Truth About Hillary,” rang out from all quarters. One of the most talked-about suggestions in the book was that Bill Clinton raped Hillary, an act that led to the birth of their daughter, Chelsea. Klein never states outright that a rape occurred, but he fashions a scene, based on what he claims are two anonymous sources, that leaves an impression of violence and sex.

The scene begins with a drunk Bill telling friends, “I’m going back to my cottage to rape my wife.” The book was so inflammatory — it also suggestively painted an environment of lesbianism around Hillary — that some of Klein’s conservative allies parted ways with him. Political strategist Dick Morris, no friend of Hillary’s, wrote in the Hill in 2005, “These accusations do not belong in our public dialogue.” Morris declined to comment on Klein’s latest publication.

Conservative columnist and editor John Podhoretz also was disgusted by the Hillary Clinton book.

“This is one of the most sordid volumes I have ever waded through,” he wrote in the New York Post. “Thirty pages into it, I wanted to take a shower. Sixty pages into it, I wanted to be decontaminated.”

Media Matters in America, a progressive outlet that monitors conservative media, produced an exhaustive report on alleged inaccuracies, fabrications and innuendo in the book. Both the mainstream and conservative media showed little interest in speaking to Klein. Seven years after the outcry, Klein defends the veracity of the work: “I haven’t said this yet, and I think I will say it. I stand by every word in the Hillary book to this day.”

Klein insists he maintains the highest journalistic standards; he says he does not publish a fact unless at least two sources corroborate it. He is so adamant about these principles that the first line of his current bestseller reads, “This is a reporter’s book.”

As in his previous books, his literary style in this one leans more toward the rhetorical than analytical. “The Amateur” repeats long-standing conservative opinions about Obama — that he is a Muslim, a closet socialist and riddled with delusions of grandeur.

“Ed Klein has a proven history of reckless fabrication in order to sell books,” said White House spokesman Eric Schultz. “Nobody in their right mind would believe the nonsense in this one.”

The umbrella theme — that Obama is an amateur in the White House — is established in a prologue that claims to depict a scene in Bill Clinton’s office at his home in Chappaqua, N.Y. Klein draws a portrait of a heated Clinton — “his nose was turning shades of red” — demanding that Hillary challenge the sitting president in this year’s election.

“ ‘The country needs us!’ he shouted, banging a fist on his desk,” Klein writes, basing his account on anonymous witnesses. Bill rattles off the reasons Hillary is a better candidate than Obama — strong secret polling numbers and the president’s incompetence — leading to the outburst that frames the book: “Barack Obama is an amateur!”

Philippe Reines, a Hillary Clinton aide and deputy assistant secretary of state, worked on efforts to debunk many of the claims in “The Truth About Hillary” and sees a pattern of imagined scene-setting recurring in Klein’s latest work. Of the Chappaqua incident, he said: “It’s completely fabricated. . . . At the end of the day, he’s nothing more than a congenital liar who believes if at first you don’t succeed, lie, lie again.”

In June 2009, Obama invited a group of nine eminent historians to the White House for dinner and an off-the-record discussion of presidential history, an evening Klein re-creates in “The Amateur” based apparently on one anonymous historian who attended and left disillusioned with his host. In Klein’s telling, Obama regaled the historians with a long list of his intended accomplishments as president.

“It was, by any measure,” Klein concludes, “a breathtaking display of narcissistic grandiosity.”

Douglas Brinkley, a history professor at Rice University and author, most recently, of a biography of Walter Cronkite, attended the meeting. He describes it as a casual history book club discussion — the president did not grandstand about his ambitions, nor did he discuss policy.

“It was more to talk about other presidents, not himself,” Brinkley recalled. “I found the president to be breathtakingly humble.” Brinkley said he was disappointed Klein “inflated and twisted and distorted” the meeting. “It sounds like a ‘Saturday Night Live’ skit of the reality. It’s nonsensical.”

Not only that, Klein misidentified the Rice historian, calling him David Brinkley, the celebrated television news broadcaster who died in 2003.

During the meeting, Klein writes, Obama tried out a new slogan for his administration.

“I’m thinking of calling it ‘A New Foundation,’ ” Klein quotes the president as saying.

Doris Kearns Goodwin discouraged the use of the motto. “It sounds,” Goodwin said, according to Klein, “like a woman’s girdle.”

Neither Brinkley nor another participating historian, who spoke on the condition of anonymity because of the privacy of the meeting, recalled any mention of “A New Foundation.” Goodwin did not respond to a request for clarification.

Klein’s mainstream media credentials run deep. Before moving to the Times, he was foreign editor and assistant managing editor at Newsweek. Edward Kosner, the former editor of Newsweek and a longtime friend of Klein’s, described the author as “a very serious-minded, ambitious and industrious person.” Referring to the work Klein did nearly 40 years ago, Kosner added, “I had every confidence in him as a journalist when he worked for me.” He did not remember Klein as being “extraordinarily conservative” at the time. “I think we were all kind of middle-of-the-road, slightly liberal at Newsweek in those days.”

Klein describes his departure from the Times as the result of a difference of opinion about the direction of the magazine with newly installed executive editor Max Frankel. In a phone interview, Frankel said the two mistakes in July 1987 were not necessarily the reason for Klein’s ouster, adding: “It was a series of things — his judgment and his style of operation and his taste in stories. We just completely lost confidence in him.” Having watched Klein’s subsequent literary career, Frankel added, “None of those books are the kind that normally you’d expect a New York Times person to produce.”

His former colleagues wonder how he emerged as a combative conservative targeting powerful liberals. Klein acknowledges hawkish sentiments as far back as the Vietnam War, but while working at Newsweek and the Times he realized that “it was not my business to push my personal ideology through the pages.”

He believes he has suffered not only for turning his back on the mainstream media world but also for succeeding as an outsider in the exclusive realm of conservative commentary. The left reviles him, and the right has yet to embrace him. But for a guy who can take a punch in the blood sport of politics, Klein seems to relish standing tall in the ring, waving his best-selling books:

“From the conservative point of view I’m a liberal, and from the liberal point of view I’m a conservative, and not being able to be pigeonhole me has created a lot of jealousy and anger.”