The rules of US politics are being rewritten in this electoral season. The Republican Party has been shaken to its core by the rise of Donald Trump while the Democratic contest for the presidential nomination is really a struggle for the soul of the party. The contest between Hillary Clinton and Bernie Sanders is a choice between the centrist establishment favourite and the self-styled socialist progressive insugent. Congreswoman Donna Edwards from Maryland is a powerful voice on the left of the Party. She's running for a seat in the Senate. But is America ready for genuinely left-wing politics?