Moderator Jim Lehrer sits at his desk before last Wednesday's debate between President Obama and Republican presidential candidate Mitt Romney in Denver. For third-party candidates, getting into a presidential debate is practically impossible. Pool/Getty Images hide caption

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Green Party presidential candidate Dr. Jill Stein delivers remarks during a press conference on July 11 in Washington, D.C. Paul J. Richards/AFP/Getty Images hide caption

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Green Party presidential candidate Jill Stein delivers her acceptance speech at the party's convention in Baltimore on Saturday. Laura-Chase McGehee/AP hide caption

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