A jury found ousted Illinois governor Rod Blagojevich guilty on one count of making false statements to federal officials, but was unable to reach a unanimous verdict on 23 other counts.
Blagojevich faced 24 counts in the wide-ranging corruption case including racketeering, conspiracy, mail fraud and attempted extortion.
US district Judge James Zagel said he intends to declare a mistrial on the undecided counts. Prosecutors have until September 7th to seek a retrial of the case.
US attorney Patrick Fitzgerald told reporters he will seek to retry the case.
The allegations against Blagojevich included an attempt to sell or barter the US senate seat vacated by President Barack Obama.
The former governor sat with hunched shoulders while waiting for the verdict. Afterward he told assembled reporters he intended to file an appeal.
"I didn't do anything wrong, I didn't break any law," Blagojevich said.
"Notwithstanding the fact that the federal government threw everything at me including the kitchen sink, in every count except for one they were unable to prove I did anything wrong."
Blagojevich, a Democrat ousted from office last year during his second term by the state legislature, faces a potential prison term of five years and a fine of up to $250,000 on the single guilty count.
The verdict on Blagojevich, 53, was delivered after 14 days of deliberations.
Prosecutors said he and his aides operated the state as a money machine by wringing campaign donations out of people doing business with the state.
His defence lawyers portrayed him as a talkative bumbler who was given bad advice but never received any illegal funds. In a surprise decision during the trial, Blagojevich opted not testify even after months of loudly declaring that he would take the stand in his own defence.
Mr Obama and some senior White House staffers played a peripheral role in the case which was built on FBI wiretaps.
In one tape heard by the jury, a jealous Blagojevich cursed that Mr Obama had not offered him a cabinet post or anything else in exchange for what Blagojevich judged as making a favoured appointment to the vacant Senate seat. Blagojevich ultimately appointed Democrat Roland Burris, who has since decided against running for the seat in November 2nd congressional elections.
The profanity-laced tapes made the one-time congressman and his wife Patti the object of television talk-show comedy bits. In the months leading up to the trial, the couple each made appearances on interview and "reality" shows.
Blagojevich's two daughters, 14-year-old Amy and 7-year-old Annie, accompanied their parents to court during final arguments, a move that appalled some critics.
Reuters