"There was nothing that my office did that was in any way inappropriate," Obama said at an afternoon news conference. "We just want to make sure that we are not interfering with an ongoing investigation."
Blagojevich was arrested last week for what U.S. federal prosecutor Patrick Fitzgerald called a "political corruption crime spree," including an alleged attempt by the governor to sell the Senate seat vacated by Obama.
Obama spokesman Dan Pfeiffer said in a statement earlier Monday that the inquiry showed that the president-elect's staff "was not involved in inappropriate discussions" over the selection of his successor. He also reiterated Obama's comments to reporters last week that the president-elect personally has had no contacts with the governor or his staff.
The statement said that Obama's lawyer Gregory Craig has kept federal prosecutors informed of the internal review "in order to ensure our full cooperation with the investigation" into allegations against the governor.
Pfeiffer said he will not release details of the review at least until the week of Dec. 22 at the request of prosecutors. Obama initially said the report would be released within a few days.
The corruption charges against Blagojevich have spurred an attempt by Illinois state lawmakers to remove the governor from office.
Rep. Mike Madigan, speaker of the Illinois House, said Monday that he was naming a special committee to investigate whether Blagojevich should be impeached.
"He has declined to take the opportunity to resign," said Madigan. "I think it is time to move forward with appointment of a committee of inquiry that could lead to impeachment."
Madigan said the committee will work every day except holidays.
"We're going to proceed with all due speed, but we're going to make sure that what we do is done correctly," he said.
The move comes as lawmakers convene in Springfield in an emergency special session to discuss not only the possibility of impeachment, but also stripping the governor of his power to fill the vacant Senate seat. Legislation is being proposed to authorize a special election instead.
Blagojevich had no immediate reaction to Madigan's announcement.
"Impeachment talk's nothing new for this governor," said Lucio Guerrero, Blagojevich's spokesman. "They've been talking about it for a long time."
Madigan said lawmakers had been investigating Blagojevich for more than a year on possible charges of abuse of power and ignoring directives of the legislature but had not felt impeachment might be appropriate until Blagojevich's arrest six days ago.
Madigan, who once co-chaired Blagojevich's re-election campaign, often has refused to meet with the governor or return his phone calls in recent months.
"I've had a chance to get to know Mr. Blagojevich over six years, so I was not surprised," Madigan said. "In light of what we've all seen … how can anyone be surprised?"
Madigan declined to express an opinion on whether Blagojevich should step down, saying he wanted to remain neutral as chairman of the special committee.
He said Blagojevich or his representative would be able to appear before the panel and cross-examine witnesses.
If the committee recommends impeachment, Blagojevich would be tried by the state Senate.
"We plan to proceed without delay," he said. "The governor is in a position to take actions that he deems appropriate for himself, and then the committee will react."
Madigan said the U.S. attorney's office, which has investigated Blagojevich for several years, would be asked to cooperate with the committee.
The ChicagoSun-Times reported Monday that Blagojevich spent about six hours consulting with high-profile defense lawyer Ed Genson on Sunday after meeting with him for four hours Saturday.
Lucio Guerrero, a spokesman for Blagojevich, who returned to work at his Chicago office Monday, said the governor hasn't ruled out signing a bill that would create a special election to fill the Obama Senate seat.
The incoming president of the Illinois Senate told WGN radio Monday that the easiest solution to the gridlock over filling the vacated U.S. Senate seat is for Blagojevich to step down temporarily and allow Lt. Gov. Pat Quinn, also a Democrat, to make the appointment.
John Cullerton said the situation surrounding the possibility of a special selection is "obviously very complicated," the Chicago Tribune reported.
Attorney General Lisa Madigan, daughter of the House speaker, said she has asked the Illinois Supreme Court to declare the governor unfit to hold office. That would allow Quinn to step in.
Quinn told the Chicago Sun-Times that the governor has the option of giving up his powers while keeping the title and presumably his paycheck.
"The governor can voluntarily step aside," Quinn told the newspaper. "I would become the acting governor. He would still retain the title. … That might be something they're exploring."
"There will be momentous decisions in Washington the first 100 days, and I don't think Illinois should be without two senators," Quinn said.
Guerrero has not said whether the governor would attempt to slow down the Legislature's move on impeachment.
"The governor has indicated in the past there is more to this story that he's wanting to tell at an appropriate time," he said.
Republicans claim Democrats are wavering because they don't want to risk a GOP candidate winning the special election.
Illinois Republican Party chairman Andy McKenna said the GOP plans to run television advertisements to try to pressure Democrats to hold a special election.
He said the ads will "make the point that this is the people's seat, and the people deserve a special election."