Trump is a bully. In addition, he's an adolescent one who focuses on peoples physical characteristics as a way of diminishing them. He said Perry wore glasses to make himself look smart. He said Ben Carson made Jeb Bush look like the Energizer Bunny. The highly acclaimed neurosurgeon was just an "OK" doctor. Megan Kelly was nothing special. Then, his "coup de grace" was telling people to look at Carly Fiorina's face and implying that someone with a face like hers couldn't be President.
Well, I think this kind of bullying is taking its toll. The recent Real Clear average of the now has Trump at just 24%. Down from 30% in the previous 4 polls.
I think people are finally getting tired of Trump's bullying and this may be the beginning of the end for the Republican front runner.
Reference: Real Clear Politics: http://www.realclearpolitics.com/epolls/2016/president/us/2016_republican_presidential_nomination-3823.html#polls