the last four democratic nominees have all won in iowa. san francisco chronicle political writer says many voters will have the president in mind. the big question is electability. i like this person, but i don t know if they can beat trump. this will be the first marker of who americans think can beat trump. reporter: several candidates have spent a lot of time and money in iowa. andrew yang held 78 events in the state, in just the last month. a big focus on the four front- runners. a big night for senators bernie sanders, and elizabeth warren could mark a more progressive shift for the party. no matter what your politics may be, i think we all understand that that is not the kind of person who should remain in the white house. this is the time to come up with the big solutions and get out there, and fight for them. reporter: former vp joe biden, and pete buttigieg represent the moderate candidates. we need a president who can bring us together. the decision is