A biographer who is writing a book about former President Barack Obama claims that Obama once called America “a racist society” in an unpublished manuscript from his law school days.

David Garrow, the author of the upcoming book on Obama’s life, said he uncovered lots of revelations about the former U.S. president during his research for the book, the Daily Mail reported.

Garrow, who spent a total of eight years working on the biography, told the Jamie Weinstein Show that if any of those revelations he discovered surfaced during Obama’s presidential run in 2008, the former president’s candidacy would have been derailed.

The historian said Obama wrote hundreds of pages for a proposed book along with his friend Robert Fischer in the early 1990s when the two were still in law school, but the manuscript was never published.

“Racism against African Americans continues to exist throughout American society, an admittedly racist culture,” Obama and Fischer wrote, according to Garrow. “Precisely because America is a racist society we cannot realistically expect white America to make special concessions toward blacks over the long haul. The greatest testimony to the force of racist ideology in American culture is that it infects not only the mind of whites, but the minds of blacks as well.”

Garrow said Obama reportedly wrote 140 pages on race in that manuscript, giving an insight into his thoughts as he left law school and was about to enter public life in Illinois.

He claimed that if Republican researchers got a hold of Obama’s manuscript during the campaign, it would have impacted him negatively in the campaign.

Garrow said people would be “profoundly astonished” at how much of Obama’s life has not yet been made public but added that it was not necessarily in a negative context.

He also questioned the accuracy of parts of Obama’s memoir Dreams From My Father, which was published in 2004.

Garrow conducted 1,000 interviews for his soon-to-be released book on Obama. He won a Pulitzer Prize in 1987 for his biography of Dr. Martin Luther King, Jr.