Ralph Nader says the Democrats must mount an intraparty challenge to President Obama in the presidential primary season in order to promote the liberal causes of the party. Otherwise the liberal agenda "will be muted and ignored," says the longtime activist. (Associated Press)

Photo by: George Ruhe

Ralph Nader says the Democrats must mount an intraparty challenge to President Obama in the presidential primary season in order to promote the liberal causes of the party. Otherwise the liberal agenda "will be muted and ignored," says the longtime activist. (Associated Press)