mission. i'm very committed to supporting the efforts within the region to try to take on the threat that they pose to everyone. >> all of the day's events were not so serious. in keeping with the atmosphere, trump promised to take a group of children on a helicopter ride. and followed through. i'm andy rose, reporting. hillary clinton is leading the polls in iowa. nearly 20 points ahead of her nearest competitor, bernie sanders, but the biggest challenge could be from someone who isn't even a candidate yet. vice president joe biden is weighing a presidential bid. making his calls to his supporters as he tries to make up his mind. here's what carl bernstein told us about the possible run. >> the big beneficiary of this