democrats ready to challenge president trump in 2020 is growing. senator kamala harris officially launches her campaign with a big rally yesterday. and tonight she faces audiences in the cnn town hall in iowa. jeff zeleny is there. in the midst of the -- oh, your insight, jeff. kind of wimpy. it's like a polar vortex there. tell us what you're expecting in that key state? >> it's minnesota cold here in iowa. it's very cold. we are inside but we're in front of the stage here where senator kamala harris is going to be taking questions tonight from our jake tapper and from iowa voters. we're on the campus of drake university. this is going to be the beginning of a year-long listening exercise and a shopping exercise if you will, for iowa democratic voters and some independent voters as well looking for an alternative. looking for a choice they'll be making. but senator harris delivering a