The gloves are off! Bernie attacks Warren and Biden. Why and will it work?

Bernie goes negative against his bestie Elizabeth Warren and she responds. John breaks down her response and why Bernie went negative. Sander also goes negative and John foreshadows what we are likely to see going into the next DNC debate.   John predicts Cory Booker to be the next to drop out. He even announced how he will drop and what he'll say.   Thomas examines each leading candidate's closing arguments with the latest ads.