Rezko has pleaded innocent to charges of demanding payments from firms trying to do business with the state and funneling the funds to himself or political figures he favored, the Chicago Sun-Times reported.

Rezko was a one-time fundraiser for Illinois Gov. Rod Blagojevich and Obama, who also entered into a land deal with Rezko in 2005. Obama since called the move "boneheaded" because Rezko's activities were known to be under a federal microscope at the time.

Rezko's defense team is expected to hammer at the credibility of Stuart Levine, the government's key witness, the Chicago Tribune reported. Defense attorneys are expected to question Levine's memory of events because of his alleged heavy use of cocaine and other illegal drugs.

"That clearly is the battle line they want to draw," said Zachary Fardon, a former assistant U.S. attorney who helped prosecute and convict former Illinois Gov. George Ryan in 2006 on corruption charges. "The defense wants it to be all about Stuart Levine."