After 14 years of researching former president Ronald Reagan, a prize-winning biographer is stirring controversy even before his book is released to the public.

Some historians, writers and Reagan associates are questioning Edmund Morris's decision to use a fictional narrator who interacts with Reagan as part of the narrative, the New York Times reported Saturday.

The 860-plus-page book, "Dutch: A Memoir of Ronald Reagan," is scheduled for release Sept. 30. The Times said it viewed a copy of the tightly embargoed book on the condition that direct quotations from it not be used.

Although Morris is only 59, he depicts himself in the book as a Reagan contemporary who, for example, caught a glimpse of Reagan as a teenager playing in a 1926 high school football game. The fictional Morris traces Reagan's life from his birth in 1911 through the 1990s.

"I was expecting the definitive book on Ronald Reagan," former Reagan aide Lyn Nofziger told the newspaper. "But how am I going to get the definitive book if there's a fictional character in it? Maybe if I read the whole book I would be pleasantly surprised. But just the idea of mixing fact and fiction is something that's disturbing me."

"Edmund has either engaged in an act of genius or a most remarkable leap off the precipice," Anthony Dolan, the Reagan administration's chief speechwriter, told the Times.

Morris did not return a message at his Washington home.

Reagan aides granted Morris unusual access to Reagan over the years, allowing him to interview the president an average of once a month and travel overseas with him.

Morris, who won the Pulitzer Prize in 1980 for his only other book, "The Rise of Theodore Roosevelt," signed a contract for a Reagan biography in 1985 for a reported $3 million advance. The book originally was scheduled to be released in 1991.

The newspaper said early copies of the book circulating privately include references to the fictional Morris's early diaries. Those early copies do not provide any explanation of the fictional character.

"I understand that a lot of what historians do incorporates techniques that fiction writers do," said Mark Gilderhus, author of the college textbook "History and Historians." "But there still is a difference and that is that historians should be constrained by the evidence," he told the Times.