Obama, the junior Democratic senator from Illinois, said he never thought that Rezko would ask for political favors from him because the developer had never done so, The Chicago Tribune reported Saturday.

Obama told the newspaper that for the first three offices he sought Rezko had raised as much as $250,000 – a figure higher than previously thought. Obama said he made a mistake by making real estate transactions with Rezko, who was under grand jury investigation at the time of their 2005 and 2006 dealings.

"The mistake, by the way, was not just engaging in a transaction with Tony because he was having legal problems," Obama said. "The mistake was because he was a contributor and somebody who was involved in politics."

When asked by the newspaper if he ever thought Rezko would expect political favors from him, Obama said, "No. Precisely because I had known him for (many) years and he hadn't asked me for something."