When President Obama unexpectedly won the Nobel Peace Prize in 2009, one predecessor was quick to applaud his selection for the award.

"I could not have thought of any other person that is more deserving of the Nobel Peace Prize than Barack Obama," Mohamed ElBaradei, then the director general of the International Atomic Energy Agency, said in a videotaped statement. He went on to praise Mr. Obama's commitment "to restore moral decency" to the lives of people around the world.

But this week, Mr. ElBaradei, now a prominent face of the opposition on the streets of Cairo, was sounding a different tune. "The American government cannot ask the Egyptian people to believe that a dictator who has been in power for 30 years will be the one to implement democracy," Mr. ElBaradei told CBS's "Face the Nation." He called the United States' refusal to openly abandon President Hosni Mubarak of Egypt "a farce."

Mr. ElBaradei, 68, had a fractious relationship with the Bush administration, one so hostile that Bush officials tried to get him removed from his post at the atomic watchdog agency. But as Egypt's powerful Muslim Brotherhood and the secular opposition on the streets of Cairo have increasingly coalesced around Mr. ElBaradei to negotiate on their behalf, the Obama administration is scrambling to figure out whether he is someone with whom the United States can deal.