The unexpected rise of Bernie Sanders will be on display tonight as he and Hillary Rodham Clinton meet face to face in the first Democratic Party presidential debate.
Sanders, the independent senator from Vermont, is a self-described Democratic socialist calling for "political revolution."
Clinton has increasingly moved to the left on domestic policy since announcing her campaign.
Three other candidates will be on stage tonight.
Jim Webb, Lincoln Chafee, and Martin O’Malley are looking to make up ground against the front runners.
Meanwhile, Vice President Joe Biden is still thinking about running.
If he decides to jump into the race today, there will be a spot for him on the debate stage.