The event, to be held at South Carolina State University and carried live on MSNBC from 7 to 8:30 EDT, will be the first opportunity for voters to see the Democratic candidates on stage together. It is also likely to highlight the racial dynamic of the Democratic nominating contest at a time when Obama and Clinton are campaigning zealously for black support.
African-Americans account for about half of Democratic primary voters in South Carolina, far more than in any of the other early-primary or caucus states. (South Carolina is scheduled to hold the nation's fourth primary next year, after Iowa, Nevada, and New Hampshire.) According to an adviser to Obama's campaign, he is increasingly looking at the Palmetto State as his best shot at guaranteeing a victory in next year's early primaries, largely because of the state's sizable black population.
If elected, Obama would be the first black president in U.S. history. The Obama campaign believes it needs at least one first-place finish in next year's early primaries, and South Carolina may offer its best bet.
A new Zogby International poll released on Wednesday showed Hillary Clinton at the front of the pack among South Carolina Democratic voters, with 33 percent support, compared with 26 percent for Obama and 21 percent for former Sen. John Edwards of neighboring North Carolina. According to similar Zogby polls in the four other early-primary and caucus states, South Carolina represents Obama's strongest base of support. But Edwards also has some advantages in the state; he was born in Seneca, S.C., and won the state's primary while campaigning for president in 2004.
Of course, the debate has implications far beyond the question of which candidate can best appeal to African-American and other South Carolina voters.
For Clinton, the event will be a chance to help reinforce her experience in the White House and her intimate familiarity with issues like healthcare while standing next to Obama, whose experience in national government is limited to two years in the Senate.
For Obama, the debate will be a test of whether he can translate his broad inspirational appeal into convincing answers on specific policy questions.
For Edwards, it offers a chance to reassert himself as the most preferable alternative to Clinton, a mantle that Obama took as soon as he stepped into the presidential race.
And for the rest of the field, tonight's debate will give them a chance to introduce themselves to many voters for the first time, and to make a splash.
By Dan Gilgoff