that requires motivated voters. all the campaigns are putting together extensive ground game operations of varying degrees to try to motivate them. scores of volunteers that walk in the neighborhoods, we went out with some of them yesterday armed with a new smart phone app that delivers data on possible supporters. >> we have a caucus app through our program. from that list you go out and call them and door knock. you follow up with them. >> reporter: there's 1,681 caucus sites. they want a captain to stand up. that is an enormous undertaking.