Politics Magazine
This chart shows the support for Donald Trump, compared to the two other candidates most given a chance to win the nomination (Scott Walker and Jeb Bush), among the different groups in the Republican Party's base. The numbers are from a NBC News Poll done between July 20th and 26th of a randomly chosen national sample of 3,060 Republicans, with a 2.7 point margin of error.
Surprisingly, at least to me, Trump seems to have significant support in all groups. He does best among those with less education, men, and those over 45 year's old -- but he has more support than either Walker or Bush in every single group shown. He could be a lot more formidable candidate that a lot of pundits think.