On the eve of the Iowa caucuses, many Republicans seem to think that a large segment of their party has gone barking mad. Much of the GOP establishment and the conservative intelligentsia are appalled at the prospect of a Trump nomination. At the same time, certain establishment types reportedly consider a Trump nomination preferable to a Cruz nomination — a preference that many conservatives find either (a) inexplicable or (b) confirmation that the establishment is as unprincipled as they’d thought. Meanwhile, Trump supporters cannot understand why prominent Republicans and conservatives are so opposed to a man they believe has the potential to bring significant numbers of non-Republicans and non-conservatives into the GOP fold.

Add it all up, and you have the most fascinating, tumultuous, and consequential Republican presidential race in decades.

The campaign has already offered several important reminders. It’s reminded us that GOP leaders are out of touch with many of their voters’ biggest concerns, particularly on issues such as immigration and trade. It’s reminded us that most people outside of Washington, D.C., do not view the world in rigid ideological terms. It’s also reminded us that one of the key fault lines in U.S. politics, and in American life generally, is the divide between Cosmopolitan America and Traditionalist America.

Writing at RealClearPolitics, Sean Trende explores the Cosmopolitan/Traditionalist divide in perhaps the single best article that’s yet been published about the Trump phenomenon. It’s worth quoting Trende at length:

“The leadership of the Republican Party and the old conservative movement is, itself, culturally cosmopolitan. I doubt if many top Republican consultants interact with many Young Earth Creationists on a regular basis. Many quietly cheered the Supreme Court’s gay marriage decisions. Most of them live in blue megapolises, most come from middle-class families and attended elite institutions, and a great many of them roll their eyes at the various cultural excesses of ‘the base.’ There is, in other words, a court/country divide among Republicans.

“This has been exacerbated by the crack-up of the Clinton Coalition and the rapid transformation of the Democratic Party into an aggressively culturally cosmopolitan institution (think Bill Clinton to Al Gore to John Kerry to Barack Obama). This change pushed out many of the Jacksonians that formed the backbone of the party for 150 years, creating an influx of lower-middle-class/working-class voters, in turn swelling the ranks of the cultural traditionalists among the Republicans.

“We’re left with an odd situation in which neither party’s leadership is particularly well attuned to the most important divide in American life. Democrats are openly suspicious, if not hostile, to these voters, while Republicans at best hold their noses on cultural issues if it advantages them (but they will go to the mattresses for unpopular tax cuts for wealthy Americans).

“So the Republicans offer up candidates who are from cosmopolitan America, who have their speeches written by speechwriters from cosmopolitan American, who have their images created by consultants from cosmopolitan America, and who develop their issue positions in office buildings located in cosmopolitan America. Then they wonder why the base isn’t excited. Say what you will about George W. Bush, but a large part of why he was successful was that he didn’t talk like your average D.C. denizen. He was routinely mocked by the press and his own party derided his malapropisms, but he connected with a class of voters that Republicans sure could use these days, in a way that Willard Mitt Romney never could hope to (and without resorting to the demagoguery of Trump).

“Which brings us to Trump. If there is anything positive I can say about Trump it is this: He gets this cosmopolitan/traditionalist divide, and he is the only candidate who lands foursquare with the traditionalists. He isn’t a fundamentalist, but he gets the whole ‘why can’t we just say Merry Christmas in supermarkets anymore?’ He’s a billionaire, but he gets the anger at wealthy donors that many see as perverting the political system. There’s little doubt that his hotels have employed undocumented workers, but he gets the anger at what many see as a foolish unwillingness of this country to ‘control its borders’ as the unwillingness of many in the Republican leadership to take strong, unambiguous stands on these issues (largely as a result of their own discomfort with these stands).

“How did Republicans and the political class respond to Trump initially? They made fun of how he talked. Everyone was then surprised when people whose speech patterns are among the only patterns that are still socially appropriate to mock responded by liking Trump more (I actually think Trump’s accent is one of his biggest advantages). Making fun of his hair? Think about this the next time you make fun of someone with a mullet. Expressing outrage at his politically incorrect statements? I think Kevin Drum is part of the way there in this typically thoughtful essay in which he discusses the impact that political correctness has on people who feel silenced because they don’t know how to talk. But even this reflects Drum’s own internalized belief that the politically correct way to speak is the correct way to speak, while non-cosmopolitan Americans’ response is more visceral: ‘Why the hell can’t we call them illegal immigrants? Says who?’ And Trump is the only candidate who unambiguously calls this out.

“Take Trump’s speech announcing his candidacy. David Byler and I had no idea what we were onto when David text-mined Trump’s speech and found that his announcement was the only one out of the 15 candidates’ announcements that sounded different. We (and others) took this as a sign of Trump’s quirkiness and a reason Trump wouldn’t last. But we clearly missed the boat. It was actually one of the most important data points of the campaign, and it has a lot to do with why Trump has been successful.

“We can go down the list of events in the Trump campaign since then. Cosmopolitan America sees a strong, moral — frankly ideological — interest in accepting refugees from Syria. Traditionalist America thinks that after Paris, this is insane. Which candidate is unafraid to say this unambiguously, without feeling the need to offer caveats? Traditionalist America thinks that the nation that put a man on the moon can ‘control its borders’; cosmopolitan America at best offers lip service to the need for doing so. Again, how many of the surviving Republican candidates fully side with the traditionalists? Traditionalist America wants to ‘kick the tires and light the fires’ against ISIS/Daesh, and Trump goes on Blutarsky-ish rants against them. Trump doesn’t do nuance on these issues, but the cosmopolitan Republican candidates feel the need to. (Suggest raising taxes on the wealthy, however, and all nuance goes out the window with the rest of them).

“All of this is a lengthy way of saying that Trump is a creation of the Republican establishment, which is frankly uncomfortable with many of its own voters, and which mostly seeks to ‘manage’ them. This is a group that looked at the Tea Party revolts of the past decade, looked at the broad field of Republican candidates (many of whom at least had ties to successful Tea Party revolts), and decided that none of these candidates were good enough.”

Read the whole thing.