Genson, who won renown in defending R&B star R. Kelly and former newspaper baron Conrad Black, dropped his bombshell announcement after a U.S. District Court hearing during which Chief Judge James F. Holderman released four wiretapped recordings of Blagojevich and his associates to the Illinois House impeachment committee.
Genson still needs to file paperwork with the court to formally withdraw from the case.
The news came as a surprise to Blagojevich, who found out about Genson's plans during an appearance on a Chicago radio show.
"That's the first I've heard of it," Blagojevich told reporters at WVON-AM.
Blagojevich, who said he last talked to Genson on Thursday evening, declined to comment.
Blagojevich, facing charges of fraud conspiracy and solicitation of bribery, was impeached by the Illinois House last week and on Monday faces trial in the Senate.
The governor held a news conference Friday afternoon and complained that the impeachment trial was unfair and indicated he would not attend. Instead, he and his wife, Patti, will appear Monday on "Good Morning, America" and "The View."
Blagojevich spokesman Lucio Guerrero said the governor had no immediate comment to Genson's announcement.
In recent days, Genson has seemed to be on a separate wavelength from both his client and two other defense attorneys on the case. The legal team sent mixed signals to the media regarding whether the governor planned a lawsuit challenging Senate trial rules.
Attorney Samuel E. Adam told The Associated Press on Thursday that a lawsuit was being prepared and could be filed with the Illinois Supreme Court within days. Genson told the AP that afternoon that he did not know whether Blagojevich would file a lawsuit to block the trial.
