Philadelphia hasn't exactly been ground zero for the presidential campaign so far this year. But it will be tonight.

The occasion is a nationally-televised Democratic presidential debate, and all eight of the party candidates will be in town.

Seven of the candidates will be participating in the debate, which will be take place in the Main Building Auditorium at Drexel University and will be aired by MSNBC, starting at 9 p.m.

The eighth candidate, former Alaska Sen. Mike Gravel, is planning his own event at the World Cafe Live. MSNBC chose to bar him from the debate on the grounds that he hasn't done enough to qualify as a real candidate.

As for the debate itself, both Sen. Barack Obama of Illinois and former Sen. John Edwards of North Carolina recently have adopted more aggressive approaches in talking about the front-runner, Sen. Hillary Rodham Clinton of New York. The question is how aggressive they will be when sharing the stage with her.

Several demonstrations are planned for the streets of West Philadelphia, including a Halloween-themed march by backers of universal healthcare and increased funding for AIDS treatment and research.

As a result of the debate, Chestnut Street in the area will be closed between 31st and 33rd Streets until 3 a.m. Wednesday.