The book is 1,078 pages long.
The Pulitzer Prize-winning author behind the latest biography on Barack Obama has revealed his effort to construct the most comprehensive story on the 44th American president.
Read: President Obama Twice Proposed to College Girlfriend Before Michelle, New Book Reveals
“My goal is to get the story right, to get the facts nailed down and to do that you have to go and interview 1,000 people,” he told Inside Edition.
David Garrow wrote Rising Star: The Making Of Barack Obama, which reveals that as a young man and long before Michelle, Obama asked his then-girlfriend, Sheila Miyoshi Jager, to marry him — twice.
Both times, Jager turned him down.
The DailyMail.com recently obtained a photograph of Jager walking in the street. She is currently an associate professor and director of the East Asian program at Oberlin College in Ohio.
Click Here to Read an Excerpt of 'Rising Star'
Garrow believes that if Jager had accepted the proposals, he would not have been president.
"If Barack had gone back to Chicago with Sheila as his spouse, I think a lot of black Chicago would have looked askance at a young man seeking to run for office on the South Side with this somewhat exotic, multi-ethnic spouse," he told Inside Edition.
Although they were still dating, Obama at some point determined it was time to move on. He then met Michelle Robinson and everything changed.
"For Michelle Robinson-Obama to be a lifelong black South Side Chicagoan, unquestionably African-American, that really helps Barack’s identity in black Chicago," Garrow said.
Garrow added that as early as his days at Harvard Law School, Obama saw himself as a potential future president.
Read: Girl, 8, Tells Obama in Adorable Letter to 'Wear Tie-Dye,' 'Do Something Fun,' He Responds
"From day one at Harvard, everyone recognizes that this is someone who is going to be a politician," the author said.
Michelle was a critical factor in her husband’s political career. In fact, she was his secret weapon when he ran for the senate in 2004. Campaign staff members wanted billboards that they thought would send a subtle, but important message.
"Within black Chicago, Barack being half black, half white, to have chosen a dark skinned black woman as his wife, not someone of lighter complexion, not someone white — that is viewed as a statement of fundamental black identity," the author said.
President Obama was not interviewed for the book, but did sit down with Garrow in the White House.
"He read the entire first 10 chapters of this book, sat there giving me a reactions — pro or con,” Garrow said.
Watch: As Obama Closes a Chapter on American History, Donald Trump Begins to Write His
