Florida once again is a crucial battleground in the presidential campaign. Donald Trump has been there for several days, telling voters, "I'm back in my second home, Florida. I love my second home. I love Florida." Hillary Clinton will be there today and her running mate, Tim Kaine, has reminded voters just how important a role they're going to play. "You're a checkmate state, if Hillary wins Florida, she's going to be president." Professor Susan MacManus, who teaches political science at the University of South Florida, joins us from Tampa with an update.