Oprah's appearance could help raise Obama's profile in South Carolina.
COLUMBIA, South Carolina (CNN) - Citing "overwhelming excitement," Barack Obama's campaign in South Carolina is out of free tickets for this weekend's rally with Oprah Winfrey, a signal that Oprah's impact could be significant in this state where Obama is still trying to introduce himself to primary voters.
Though Oprah's appeal certainly transcends race and class, black women are proving to be a key subset of voters in South Carolina, and Oprah's presence on Sunday could help raise Obama's profile in a state where Sen. Hillary Clinton is still more well-known.
"What this does, is it takes somebody who ten months ago most people in South Carolina had no clue who he was, and with the media attention surrounding Oprah, it puts him front and center," said Winthrop University political scientist Scott Huffmon.
"Oprah is not going to change people's minds on her own, but Oprah makes Obama salient. So if he pulls off an upset in Iowa, suddenly he is the forefront of everyone's mind and he has the momentum. And he can use it to springboard him through in South Carolina. That's what it can do."
The Obama campaign wants this to be a huge event: The rally will take place at the Colonial Center, an arena here that seats 18,000 people. Oprah and/or Obama fans were camping out in sleeping bags outside Obama headquarters in Columbia on Saturday morning, waiting for tickets.
Assuming every ticket-holder shows up, there will be more people at the arena for a political rally than for an average University of South Carolina basketball game, which aren't usually sell-outs.
For those that didn't get tickets in time, the campaign says there is a waiting list. Obama and Oprah will also campaign in Iowa and New Hampshire this weekend.
- CNN South Carolina Producer Peter Hamby