President Obama won't be giving the speech he might wish to give tonight.
All presidents accepting their party's renomination seek to shift from a message of hope and change to one of progress and accomplishment. Although Obama will certainly talk up the highlights of his term, he won't want to sound triumphant — not with a jobs report due tomorrow that's expected to show a 43rd straight month of U.S. unemployment above 8 percent.
"In an acceptance situation, you want to paint a bright picture of all the wonderful things that have happened over the past four years," says Martin Medhurst, a professor of political science and rhetoric at Baylor University.
"While good things have happened, the economic picture is such that he'll be hard-pressed to paint a terribly bright picture," he says.
Obama's other main task — aside from knocking his opponent, Republican Mitt Romney — will be convincing voters that another four years in office will lead to greater things.
"He's got to remind people that he's done a tremendous amount and the best is yet to come," says Minneapolis Mayor R.T. Rybak, a vice chairman of the Democratic National Committee.
Rybak points to accomplishments Obama is likely to tout: bailing out the domestic auto industry, expanding health coverage for millions of Americans, reshaping the student loan business, ending the war in Iraq and winding down the one in Afghanistan, and green-lighting the mission that killed Osama bin Laden.
"He's delivered and is going to deliver a lot more than Mitt Romney can ever dream of doing," Rybak says.
As has been the case throughout the Democratic convention and the campaign as a whole, attacks on Romney's platform will certainly be a hallmark of Obama's speech.
"Both of them have to savage their opponent," says George C. Edwards III, a presidential scholar at Texas A&M University who has written a book about Obama's leadership titled Overreach.
"Obama has to frame the election as a choice, not a referendum [on his own record] — 'I'm better than the other guy,' " Edwards says.
Obama will seek to raise doubts and fears about what a Romney administration would look like, arguing above all that it would imperil the middle class. And he'll be taking a page or two from the 1936 renomination acceptance speech of Franklin D. Roosevelt, Baylor's Medhurst suggests. Seeking a second term in the face of continuing depression and tremendously high unemployment, Roosevelt argued that the "economic royalists" in the Republican Party favored the rich, while he was for the little guy.
That fall, Roosevelt went on to win every state but Maine and Vermont.
"That's exactly the stance Obama is going to have to take," Medhurst says, "that he stands for the middle class and Romney is for the rich people."
Raising the stakes by painting a dire picture of a Romney presidency may be enough to prod the Democratic base, which has been noticeably less energized about this election than it was about Obama's run four years ago.
"I don't think he can recapture the magic of 2008 — no president can," says David Woodard, a Republican consultant who teaches at Clemson University. "But he has to make them feel he can lead them to victory."
Obama also has to speak to those other potential supporters who are disillusioned but might still be won over.
Romney and other Republicans sought at their convention last week to portray Obama as a well-intentioned man who has failed, so that voters will not feel bad about booting out a personally popular president.
"He's been president for four years, and I'm not sure the average person right now could answer the question, 'What does Barack Obama want to do in a second term that would have a better result?' " says Gary Bauer, chairman of the Campaign for Working Families, a conservative political action committee.
The theme of the Democratic National Convention has been "Forward." Obama has to answer the question, "Forward to what?"
"The challenge for Obama is that he needs to put out, much more than he has, a strong vision for what he wants to do in a second term," says Michael Waldman, a former speechwriter for President Bill Clinton and president of the Brennan Center for Justice at New York University's law school.
"Not an imaginary vision of what he would do if Democrats had all the power," Waldman adds, "but, realistically, what people could expect from him if elected for a second term."