Illinois Gov. Rod Blagojevich, shown Dec. 8, was still ignoring calls for his resignation on Thursday. The state's attorney general said she may go to court to have him declared unfit to govern. (Scott Olson/Getty Images)

Barack Obama strongly asserted on Thursday that none of his staff members was involved in the alleged conspiracy over the selling of the president-elect's vacant Senate seat by Illinois Governor Rod Blagojevich.

"What I'm absolutely certain about is that our office had no involvement in any dealmaking around my senate seat — that, I’m absolutely certain of," Obama told reporters. "That would be a violation of everything that this campaign has been about. That's not how we do business."

Obama said he was "appalled and disappointed" over the revelations and repeated that he never spoke about the subject with the governor, who is charged with conspiracy and solicitation to commit bribery.

Prosecutors have been quick to point out that Obama is not accused of any wrongdoing.

Obama added that neither he nor his staff have been contacted by federal officials in connection with the probe.

He urged Blagojevich to step down, saying he can no longer effectively govern.

"I hope that the governor himself comes to the conclusion that he can no longer effectively serve and that he does resign," he said.

Hours earlier, Illinois's attorney general threatened to go to the State Supreme Court to declare Blagojevich unfit for office if he doesn't step down.

"The easiest way for us to move on in the state of Illinois is for Governor Blagojevich to do the right thing for the people and to resign," Attorney General Lisa Madigan told CNN on Thursday. "Now, it doesn't appear that he has any inclination to do that. Maybe things will change today or tomorrow."

On Wednesday, Blagojevich ignored calls for his resignation. He reported for work, a day after he was arrested at home on accusations he was conspiring to sell Obama's vacant Senate seat, for which he has the power to appoint someone. He was later released from custody and denies any wrongdoing.

"I have the opportunity to go to our Illinois Supreme Court and ask them to declare our governor is unable to serve and put in our lieutenant-governor as acting governor," Madigan said.

Aides say they were mistaken

Obama's comments Thursday came as some Republicans criticized him for not commenting on his connections to Blagojevich.

Obama's transition team has put distance between the president-elect and the governor. They have acknowledged that Obama endorsed his fellow Democrat for the governorship in the past but have stressed the two did not have a close relationship.

In previous interviews, members of Obama's transition team have said the president-elect discussed the issue of the Senate seat with Blagojevich and that he was among the top strategists of Blagojevich's 2002 gubernatorial victory. But his aides have since backed down from those remarks and said they were mistaken in their assertions.

An FBI affidavit said Blagojevich was intercepted on wiretaps conspiring to sell or trade the vacant Senate seat for personal benefits for himself and his wife.

Prosecutors allege Blagojevich wanted a cabinet post, placement at a private foundation in a significant position, campaign contributions or an ambassadorship in return for the Senate seat.

The 76-page affidavit alleges the 51-year-old Democratic governor even considered appointing himself if he wasn't offered anything of value.

It is also alleged he initiated various other so-called pay-to-play schemes while in office to extract money from state contractors.

The affidavit also claims Blagojevich pressured the Tribune Co. to fire editorial writers at the Chicago Tribune newspaper over several negative editorials about Blagojevich and threatened to withhold state assistance for the company's sale of Wrigley Field if the demand was not met .

With files from the Associated Press