ANKENY, IOWA, Jan 27: At nearly nine p.m. on Saturday, Samy Amkieh was about to head back to his office after braving 20 degree temperatures to knock on doors for three hours in East Des Moines. But the 20-year-old field organizer knocked on one more door and was rewarded by convincing the resident to be a team leader for Bernie Sanders at a nearby caucus location.