reporter gary hayes is in des moines, iowa with the behind the scenes dual between the top two republican canidates. >> reporter: in a converted store front headquarters outside des moines an army of ted cruz supporters get their final marching orders. >> i can not stress enough how important it is to call today. calling is more important than walking today. hundreds of volunteers all over the country dialing a cultivated list of iowans. ted from arlington, virginia got here last week. >> the first day i called ten hours straight. >> reporter: cruz's volunteers stay in dorms nearby. majority followed him from his texas gig. >> everybody has been so welcoming and so caring and it has been a blessing. >> reporter: trump's iowa headquarters sits a few miles down the road. the biggest mystery in iowa today is what is going on inside this building? donald trump's iowa campaign headquarters is locked down to reporters and the campaign isn't talking about their ground game. we went inside and were asked to leave. we stopped this man coming outside with trump swag in his hand. >> i waited for a d