Rahm Emanuel, the White House chief of staff, said in an interview that the president intended to use the news conference as a “six-month report card,” to talk about “how we rescued the economy from the worst recession” and the legislative agenda moving forward, including health care and energy legislation, which squeaked through the House and faces a tough road in the Senate.

Polls show that Mr. Obama is more popular than his own policies, a worrisome sign for a president with such an ambitious agenda. Mickey Edwards, a former Republican congressman who is now vice president of the Aspen Institute, said Mr. Obama might be making a mistake in reading his election as a mandate for dramatic change.

“A lot of people supported Obama because they wanted to repudiate the Bush administration,” said Mr. Edwards, who backed Mr. Obama for president. “I was one of those people who supported him for reasons other than the policies he is proposing. He seemed more thoughtful, more contemplative — I felt he had the right temperament to be president. But I think his health care proposal goes beyond what the public at the moment is ready to accept.”