While Obama is not accused of any wrongdoing and has subsequently donated all the money raised by influence-peddler Antoin "Tony" Rezko to charity, prosecutors have alleged that some of the kickbacks ended up in the Illinois Democratic senator's campaign coffers.

Obama is also under fire for entering a land deal with Rezko in 2005 when it was widely known that the real estate developer was under federal scrutiny, something Obama later called a "boneheaded" move.

The trial in a Chicago federal courtroom is expected to last months and Obama's name came up on day one, when the defense noted in opening statements that Rezko had not only raised money for the charismatic politician, but had tried to hire Obama while he was still studying at Harvard law.

"Of all the politicians he supported, not one of them will come here and say he asked for anything for himself," defense attorney Joseph Duffy said as he argued that the Syrian-born businessman's fundraising stemmed from a passion for politics rather than self-interest.

It is unlikely that Obama will be called to testify on his friend's behalf, Duffy told reporters.

"I can assure you he's not been subpoenaed by the defense," he said. "There's no intention to do that."