http://www.slate.com/articles/news_and_politics/politics/2015/09/donald_trump_and_ben_carson_argue_over_the_presidency_the_fight_between.html

Ben Carson doesn’t want to get into a close punch and shove with Donald Trump. The two bumped into each other last week, when Carson seemed to question Trump’s faith. But before it could get out of hand, Carson apologized. That’s probably a good strategy. Every candidate who has attacked Trump—with the exception of fellow nonpolitician Carly Fiorina—has fallen in the polls. Carson, for his part, is gaining on Trump, pulling even with him in Iowa and in national polls. In the latest CBS/New York Times poll, Trump is at 27 percent and Carson is at 23 percent, up from 6 percent in August.