CHICAGO - President-elect Barack Obama said Thursday that he was "absolutely certain" no member of his staff was involved in discussing deals for his Senate seat with disgraced Illinois Gov. Rod Blagojevich.

Blagojevich was arrested Tuesday on charges that he put Obama's seat up for bidding.

The governor has ignored calls for his resignation and retains the power to appoint Obama's replacement.

Obama said he was "as appalled and disappointed as anybody" by the allegations.

Aiming to put to rest any questions about involvement by any of his staff, Obama said he never spoke to Blagojevich about the choosing of his successor.

For the first time, he also addressed the issue of whether his transition staff had any contacts.

"I am confident that no representatives of mine would have any part of any deals related to this seat," Obama said. "I think the materials released by the U.S. attorney reflect that fact."

As to whether any aides were involved in Blagojevich's alleged dealmaking schemes, he said he was "absolutely certain" they were not.

The president-elect, who has called on Blagojevich to resign, says he feel a "public trust has been violated" and that he doesn't think the governor "at this point can effectively serve Illinois."

Also at the news conference, he introduced former Senate majority leader Tom Daschle as his choice to be secretary of health and human services and said he favoured congressional passage of short-term loans to rescue the U.S. auto industry.

The choice of Daschle had been known for some time, but it was only made official on Thursday.

Obama described the former South Dakota senator as "one of America's foremost health care experts."

He said Daschle will also be overseeing a new White House Office of Health Reform.

Daschle was a close adviser to Obama throughout the campaign. He recently wrote a book on his proposals to improve health care.