CHICAGO — President-elect Barack Obama said yesterday he's "absolutely certain" no one close to him was involved in an alleged plot by Gov. Rod Blagojevich to sell his former Senate seat to the highest bidder. At the same time, Obama announced an internal investigation into contacts his aides may have had with the embattled governor.

At a news conference to introduce former Senate Majority Leader Tom Daschle as his pick as secretary of health and human services, Obama said he has not spoken to investigators who accused Blagojevich this week of using his authority to name Obama's replacement to barter for campaign cash or a high-paying job inside or outside government. It was less clear whether investigators sought to have conversations with his aides.

"I have not been contacted by any federal officials," Obama said. "And we have not been interviewed by them."

Obama sought to end questions about whether members of his staff were involved in Blagojevich's alleged schemes by announcing that he has ordered an internal probe of all contacts between his transition staff and Blagojevich's staff. He promised to make the results public "in the next few days."

"What I'm absolutely certain about is that our office had no involvement in any dealmaking around my Senate seat," he said.

Obama said he was "appalled and disappointed as anybody" by the accusations that Blagojevich tried to profit from his authority to appoint his Senate successor. The governor has ignored calls for his resignation, including one that Obama repeated yesterday, and has declared his innocence. He retains the power to appoint Obama's replacement.

Daschle, whose selection was revealed weeks ago, will be Obama's point person in both designing an overhaul of the nation's healthcare system and shepherding it through Congress. Besides heading the Health and Human Services Department, Daschle also will lead a newly created White House Office of Health Reform.

Obama named Jeanne Lambrew, a Daschle collaborator and Clinton-era adviser, as the No. 2 person in the new White House office.

Obama called yesterday's news conference to highlight his healthcare plans and to lobby for congressional passage of short-term loans to rescue the U.S. auto industry. But all but one of the questions from reporters focused on the Illinois corruption scandal.

Nothing in the federal complaint suggests any wrongdoing by Obama or his staff. But the accusations against Blagojevich are an unwelcome distraction to the presidential transition, raising questions of whether Obama can follow through on his message of change and clean government.

The complaint, for example, says Blagojevich discussed having an unnamed Obama adviser help raise $10 million to $15 million for a nonprofit group that the governor wanted to create.

Obama, for his part, declined to comment on the adviser's identity.

"I'm not really certain where the investigation is going forward," he said

Obama said the charges against Blagojevich grew out of a culture that views politics "as a means of self-aggrandizement."

"That's exactly what has to change," he said.