Marco Rubio's newly aggressive posture toward Donald Trump is all about delivering low-blow insults, and reflects a popular — but incorrect — notion among Republican elites that Trump's not-very-orthodox ideology is succeeding because of the force of his personality. But Trump isn't winning because he's a buffoon. If anything, he is winning despite being a buffoon. He is winning because he understands that nationalism is more important to real-world conservative politics than free market dogma, and he offers what conservatives care about: a populist nationalism that is inflected with conservative policy commitments but by no means limited to them.

Trump is winning because he understands that the 2016 race is about the very definition of America itself. For candidates like Rubio — following the pace set by Barack Obama and Hillary Clinton — it's about embracing a new, more diverse, more tolerant country. For Trumpers, it's precisely the opposite. They want to put the Obama genie back in the bottle and fight vigorously for the traditional notion of Americanness, at home and abroad, even if it means jettisoning some of the GOP donor class's ideological bugaboos.

Trump has a reasonably coherent ideological vision

Trump is, of course, a joke when it comes to discussing policy details. But that doesn't mean he doesn't have a real agenda. Indeed, in the United States it's actually common for ideologically rigorous candidates — including mostly conservative Republicans but also Bernie Sanders — to speak in terms of grandiose and likely unachievable visions rather than in wonkish, nitty-gritty details.

And what is Trump's agenda? A revived and unapologetic American nationalism, which will stand for American interests abroad while defending the traditional conception of the American nation at home. This line runs through Trump's views on a wide range of issues:

On trade, he wants to revise existing deals and replace them with ones that the United States will "win."

On foreign policy, he is suspicious of idealistic ventures but willing to be maximally brutal and maximally avaricious when force does need to be used.

On drug prices, he wants the US government to stop acting like the biggest sucker in the world by letting itself get ripped off by rootless multinational firms.

On immigration, what really needs to be said.

Trump's speeches these days also loudly and proudly invoke support for veterans and law enforcement, identifying his movement with the agents of the state.

More subtly, Trump breaks with conservative orthodoxy by opposing cuts to Social Security and Medicare, positions that research by Donald Kinder and Cindy Kam find to be associated with white ethnocentric sentiment.

It's important to see how some of the real and perceived shortcomings of Trump's policy thinking feed into the broader narrative of nationalism.

Wonks' mockery reenforces his nationalism

Wonks sneer, for example, that there is simply no way Trump is going to be able to force the Mexican government to pay for a wall across the border. The point of the promise, however, is not particularly that people believe Trump will make it happen or even necessarily care who pays for the wall. The point was revealed in the last debate, when a moderator asked Trump about former Mexican President Vicente Fox's statement that "I'm not going to pay for that fucking wall" and Trump immediately quipped that the wall just got 10 feet higher.

The point, in other words, isn't about wall construction. It's about Trump signaling that he wants to take a punitive attitude toward Mexico and an unapologetic attitude toward cracking down on illegal immigration. The wall says that Trump's thinking on the matter is untouched by humanitarian concern or high-mindedness.

Similarly, economists argue that Trump's talk of winning or losing trade deals is nonsensical — the gains from international trade aren't zero-sum. But that's how economists, and the global elite more broadly, think about it, because they're not nationalists.

In the competition for internal power and prestige, economic development most certainly is a zero-sum game. And whether or not you think the United States has benefited from global economic integration over the past 25 years, it's unquestionable that China has benefited more.

"My whole life I’ve been greedy, greedy, greedy. I’ve grabbed all the money I could get," Trump says in one of the best lines to appear in his stump speech. "I’m so greedy. But now I want to be greedy for the United States."

Trump defends traditional American identity

Donald Trump is obviously not a devout Christian or a serious believer in any religion. Nevertheless, he professes to be seriously disturbed by the "war on Christmas," and says, "If I'm president, you're going to see 'Merry Christmas' in department stores."

The freakout over Trump on the part of the conservative establishment has prompted some of its members to begin noting that the president has no constitutional authority to control who says, "Happy Holidays," and who says, "Merry Christmas." But of course it was perfectly mainstream conservative figures who launched the war on Christmas narrative, never mind constitutional scruples.

The crux of the matter, anyway, is about culture and identity rather than religion or policy.

Indeed, as Elizabeth Bruenig writes, "Saying 'Merry Christmas' — and the practice of shopping in massive department stores for huge quantities of goods to distribute to friends and family — are by no means integral to the Christmas holiday" in the first place.

These are American traditions rather than Christian ones, but they are traditions of the subset of Americans who either practice Christian faith or hail from families that historically did.

And that is in many ways the essence of Trumpism. Americans these days are bombarded by messages telling them — accurately — that the country is changing. It is getting less white, and more Latino and Asian every day. We are electing black presidents, listening to Chris Rock deliver primetime lectures on racism, celebrating trans women, and witnessing same-sex marriage move from the political fringe to the mainstream in the blink of an eye.

Trump stands athwart history yelling, "Stop"

Marveling at the early days of Trump's rise, conservative pundit Ben Domenech asked, "Are Republicans for freedom or for white identity politics?"

It's a good question, but the founders of the modern conservative movement would find it strange to see that the vast majority of their institutional descendants side with freedom while it's left to a vulgarian outsider like Trump to stand up for identity politics.

National Review founder William F. Buckley Jr. was, after all, the author not just of "Why the South Must Prevail" but also of a famous mission statement that said the magazine "stands athwart history yelling 'Stop,' at a time when no one is inclined to do so, or to have much patience with those who urge it."

That is Trump in a nutshell: a candidate for the people who don't agree that all this hope and change has been for the better, and who want to, as the man says, Make America Great Again.

Marco Rubio is the perfect foil

Against this populist-nationalist insurgency, the Republican establishment has chosen as its champion literally the single human being in all of conservative politics least suited to co-opting the sentiments of Trumpism.

Back when the media — and much of the party elite — were proclaiming Rubio to be "the Republican savior," they were making a calculation that is 180 degrees opposite from Trump's calculation. Looking back on the seesaw of 21st-century politics, they saw that the George W. Bush administration had essentially trashed the country. Then they saw a Tea Party wave that they willfully chose to interpret as a grassroots movement calling for a more rigorous dedication to free market ideology. Then they lost in 2012, and chose to interpret that loss as reflecting their party's inability to connect with the emerging young, diverse electorate.

Into the breach stepped Rubio, a Tea Party Republican who also happens to be a young, hip Latino guy with an affection for gangster rap and EDM.

The Rubio gambit, in short, is that Republicans should surrender to Obama-era cultural change, that they ought to embrace it and simply position their party as having a tax-cutting, spending-hating, free-trading, war-fighting ideology that Americans of all skin tones and musical tastes can learn to love.

Writing at a time when American parties were oddly unpolarized around economic issues, National Review editorialized in favor of a more robust two-party system:

The most alarming single danger to the American political system lies in the fact that an identifiable team of Fabian operators is bent on controlling both our major political parties (under the sanction of such fatuous and unreasoned slogans as "national unity," "middle-of-the-road," "progressivism," and "bipartisanship.") Clever intriguers are reshaping both parties in the image of Babbitt, gone Social-Democrat. When and where this political issue arises, we are, without reservations, on the side of the traditional two-party system that fights its feuds in public and honestly; and we shall advocate the restoration of the two-party system at all costs.

Contemporary politics is, of course, sharply polarized around precisely these issues.

But Rubio reflects an impulse by conservative leaders to flatten the lines of cultural conflict. In a universe where the Republican Party is not exactly lacking in older white male leaders with decidedly square musical taste, their leadership wants to ape fresh-faced liberalism.

But many Americans are old, white, uncool, and perhaps even retrograde in their cultural and racial views — they want a party to represent them more than they want a party that adheres rigorously to the dogma of capital gains tax cuts and entitlement reform. Many fairly conventional Republicans could have offered something to such voters, particularly if the party establishment were willing to concede a little flexibility on at least some areas of economic policy. But the establishment offered instead Jeb Bush of the childhood in Venezuela and the Mexican wife, and then the Gang of Eight member with cool boots.

Is it any wonder Trump is winning?