We are not just red states or blue states but the United States, Obama says now. The sentiment is certain to be heard in his speech, if dressed in new words. Can Americans truly rally together behind such a call?

"Isn't it pretty to think so?" Ribuffo muses. "The problem is, all presidents want to bring the country together on their own terms.

"I think Americans understand really that an inauguration is like a graduation or a wedding. There's a kind of rhetoric of great optimism and then afterward, well maybe the graduate doesn't get the greatest job in the world. Maybe the marriage is a little rocky. But today, at least, let's look on the bright side."

Lincoln's second inaugural speech, coming with Civil War victory days away and his assassination the following month, made the transcendent appeal for national reconciliation, "with malice toward none, with charity for all." It was a short speech, loaded with religious touchstones, and perhaps the greatest inaugural address of all.

But his unity was achieved by force of arms, not rhetoric.

Roosevelt embodied hope, change and the possibility of having security and even prosperity once again, speaking in 1933 to a nation in the roughest grips of the Depression.

Obama has spoken lately about how bad things are. He can be expected to address how good things can be again. He already has been invoking FDR, obliquely, in reminding Americans that previous generations have faced down war, depression and "fear itself."

"We're in a sour mood, we're pessimistic," said Stephen J. Wayne, government professor at Georgetown University. "The new president has to try to restore hope and confidence and try to restore the proposition that had been so valid for many years — that the future is going to be better than the present."

FDR railed against the moneychangers in a speech delivered in the midst of a bank panic, with one-quarter of the work force idle. His words were angry and hopeful at once.

He advanced a thought that is foreign to the ears of the modern consumer — that the crisis concerned, "thank God, only material things."

"Only a foolish optimist can deny the dark realities of the moment," he said. "Yet our distress comes from no failure of substance. We are stricken by no plague of locusts."

The fundamentals are strong, you might say.

Kennedy embodied hope, change, common purpose and of course the passing of the torch to a new generation.

Obama is not waiting for Jan. 20, He has asked Americans to "insist that the first question each of us asks isn't 'What's good for me?' but 'What's good for the country my children will inherit?'"

Expect that thought to be expressed more poetically on Inauguration Day, in the spirit of Kennedy's call: "Ask not what your country can do for you. Ask what you can do for your country."