According to the book, Blagojevich was recorded saying he believed Tony Rezko, who was convicted on corruption charges, gave Obama the cash. The book says federal authorities reportedly looked into the allegation, but ultimately gave it little credence.
The Chicago Tribune reports federal authorities declined to comment on the claim and Obama's campaign dismissed it as "preposterous" and "false." An attorney for Rezko also denies the allegation.
The book is called "Golden: How Rod Blagojevich Talked Himself Out of the Governor's Office and into Prison".