CHICAGO -- A long-time friend and fundraiser of presidential hopeful Barack Obama was accused by prosecutors Thursday of using his political clout to carry out a kickback scheme aimed at extorting millions from firms trying to do business with the state of Illinois.

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 Rezko dealings will likely dog Obama as he vies for the Democratic presidential nomination.

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."

Prosecutors, however, have stayed mum on their potential witness list.

They argued Rezko used his influence as a top fundraiser for Democratic Illinois Governor Rod Blagojevich to get friends and associates appointed to key state boards.

"Rezko was the man behind the curtains, pulling the strings," assistant US attorney Carrie Hamilton told the jury.

"Rezko had the clout to get people on board and off boards," she said. "He was willing to use this clout for cash."

Rezko used his influence on one such board to get a controversial hospital project approved in exchange for a share of a million dollar kickback from a construction company, she alleged.

He also pressured investment firms to pay "finders fees" in exchange for help getting the business of a massive public pension fund with the assistance of a corrupt board member who eventually cooperated with prosecutors, she said.

Key to the case is the role of Rezko's chief co-conspirator, Stuart Levine, who has reached a plea deal with prosecutors.

The defense argued that Levine, a Republican, was desperate to maintain his political clout after a Democrat won the governor's mansion for the first time in decades.

It said Levine lied about his relationship with Rezko in order to first hold onto power and then to save his own skin when the FBI caught wind of his schemes.

Prosecutors said they would provide proof that Rezko was actively involved in the kickback schemes and said the money was funneled to Rezko's associates to hide it.

Rezko is charged with 15 counts of fraud, six counts of aiding and abetting in the solicitation of bribery, two counts of money laundering and one count of attempted extortion.