CNNMichelle Obama: 'When they go low, we go high'CNNPhiladelphia (CNN) Michelle Obama cast the presidential race as one between a positive role model for children -- in Hillary Clinton -- and a damaging one -- in Donald Trump -- in the marquee speech on the Democratic National Convention's opening night.The Daily 202: Michelle Obama is the Democrats' best weapon against Donald TrumpWashington PostWhy Michelle Obama's DNC Speech MattersNBCNews.comMichelle Obama isn't running for office yet.