Bernie Sanders defeated Hillary Clinton in Michigan yesterday. It's already being called, "One of the greatest upsets in modern political history." That's not just from Sanders' campaign but respected pollsters -- now trying to figure out why they were so wrong. In advance of the voting, With another debate tonight in Miami, Democrats are figuring how to keep the party together as the battle goes on. Clinton's still likely to have the delegates needed to win the nomination. Can she avoid repeating the mistakes of past divided conventions?