When Donald Trump reached the top of the polls in July, his candidacy seemed very familiar, at least to me.

His coalition was ideologically incoherent, and he had no support from party elites. His surge looked like a media-driven phenomenon with no foundation — exactly the sort of candidacy prone to collapse once coverage turned negative. It was a story that played out over and over again in the 2012 campaign.

Two months later, Mr. Trump has not gone bust, as I thought he would. He has demonstrated that he can drive the media as much as the media is driving his support. And his coalition is united as much by affection for his demeanor as his policies — insulating him from fallout over inflammatory remarks that would doom other candidates.

Suddenly, the question isn’t whether Mr. Trump is different from someone like Herman Cain in 2012, but how different? Is he so different that he could survive not just for a month or two, but all the way to Iowa and New Hampshire? Is he so different that he could even win?