Chicago ? President-elect Barack Obama said Thursday 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.