Donald Trump on CNN

Donald Trump has made a huge mistake.

Ben Carson is far and away the most personally popular candidate in the GOP race. His inspiring life story speaks to large constituencies in the party, ranging from evangelical Christians who love tales of redemption, to economic conservatives who treasure Horatio Alger narratives of the poor pulling themselves up by their bootstraps. As a successful black man who supports hard-line conservative policies, he’s a cherished piece of evidence that the GOP is as it claims to be: a party for all races. 

Trump, in likening Ben Carson’s allegedly “pathological” violence to the incurability of a child molester, is running a huge risk by slinging mud at a beloved figure in an utterly unconvincing way. The 2016 campaign is littered with the columns of pundits who have proclaimed the end of Trump’s run, but even by the standards of Trump’s earlier crass and demeaning insults, this attack is a new low. And with Carson closing in on Trump in the national polls, it comes across as desperate.

Trump has a much harder time going after rivals who aren’t white men. When attacking, say, Jeb Bush, Trump almost always has good instincts for weak spots, like his brilliantly effect taunt that Bush is “low energy.” When going after Carson or Carly Fiorina, Trump seems baffled, and ends up resorting to crude racially and sexually charged comments. The fact that Carson and Fiorina have caused Trump problems shows that even the limited diversity of the GOP has some value.