prompted this re-tweet, ben carson is now leading in iowa, too much monsanto in the corn creates issues in the brain? within hours he deleted the tweet and said, quote, the young intern who accidentally did a retweet apologizes. cnn reporter nia-malika henderson is with me. what s behind dr. carson s rise? people really like dr. carson in iowa. he hasn t been there much over the last six weeks or so, but he had a ground game really in the summer, i think we re starting to see some of the fruits of that labor. he ll be there tomorrow as well. he s on book tour now. he knows his audience almost more than anybody in this race. trump does too, but he knows the things that he sometimes say actually resonates with the people in his audience and the people who have liked him. i think we ve got him commenting on how he s doing so far in this race speaking from kansas.