Author David Maraniss on his book 'Barack Obama: A Story,' says he wrote the book as a historian, not a fact checker

A new biography about President Obama sheds a unique light on the president's past. It's generating lots of buzz because it questions President Obama's history and his memoir, which is called "Dreams Of My Father."

Author David Maraniss traces several generations of the president's lineage in his book, "Barack Obama: A Story," from Kenya to Kansas and gives an unprecedented look at young Barack Obama's life before his career in politics ever began.

Maraniss talks with Soledad this morning on "Starting Point" and explains that he didn't sent out to write the book to challenge President Obama's memoir.

"I'm not writing it as a fact checker," Maraniss says. "I'm writing it as an historian. Other people for ideological reasons are pouncing on that part of what my book is, but in fact I'm trying to tell the truth."

"A memoir is far different from rigorous factual biography," Maraniss says. "It's not as though I'm trying to say, aha, I got you, at each point, I'm just trying to present the way I really found it, which in many cases was different from what he presented."