Running respectively in the Republican and Democratic primaries for President, Donald Trump and Bernie Sanders have attracted much more support than the party establishments expected.

They didn’t expect it because, in prior presidential-election cycles, men like them would almost certainly have been marginal candidates destined to drop out early. That hasn’t happened, and at this point probably won’t. Why not?

I don’t know a single Republican in the flesh who supports Trump, yet he just finished second in the Iowa caucuses and holds a substantial lead in the polls for next week’s New Hampshire primary. Most people I know dismiss him—rightly or wrongly—as a raging, narcissistic buffoon. His style is indeed reminiscent of the staged confrontations of the professional-wrestling scene he has helped finance. On one occasion, he even joined in the trading of insults between wrestlers.

That style obviously attracts a certain demographic, but that demographic is relatively limited. What many more Trump supporters say is that he “tells it like it is.” Never mind that he does not seem to have developed a broadly coherent set of political positions. Appealing to both justified and unjustified resentments about immigration has garnered him a lot more support. There is an explanation for that, but reducing it to mere racism and xenophobia, as many Democrats do, is far too simplistic.

Sanders, an avowed “democratic socialist,” has so far garnered more support than any other socialist in the history of presidential politics—including Norman Thomas, who ran repeatedly in the 1930s and 40s when the working class was traumatized by the Depression. And Sanders does it running in the Democratic primaries as an “independent,” not as leader of a third party like Thomas. In the Iowa caucuses he came out in a virtual tie with Hillary Clinton, who as the presumptive front-runner has a larger and far-better-financed organization. Is that because so many Democrats have converted to straight-up socialism in the last few years? Rather unlikely.

According to R.R. Reno, editor-in-chief of First Things, there is a unitary explanation for the rise of each candidate, despite the difference of party and style: the increasing de facto disenfranchisement of the economically struggling white middle class. The standard messages of each major party, he argues, only make that fact seem irrelevant, thereby stoking the fears and resentments it has been causing. Each in their own way, Trump and Sanders speak to those fears and resentments, thus suggesting to many middle-class whites that they do matter to our elites.

My hunch is there’s a lot of truth in Reno’s theory, though clearly it can’t be the whole story. What do you think?