7:08AM EST October 2. 2012 - NEW YORK — Bill O'Reilly describes himself as a journalistic "watchdog" and a "champion bloviator."

He's not a historian — "not really. That's not my discipline," he says in his corner office at Fox News, home of The O'Reilly Factor, the top-rated show on cable news.

But few history books can approach the popularity of O'Reilly's Killing Lincoln, which has sold more than 2 million copies since it was released a year ago. His new book, Killing Kennedy (Henry Holt), about the 1963 assassination of President John F. Kennedy, could be as popular. It goes on sale Tuesday....