In the wake of the Iowa caucuses, the news media have decided, fairly or not, that the only Republican candidates worth paying attention to from this point forward are Donald Trump, Ted Cruz, and Marco Rubio (though the others may get a moment of consideration here and there). The three are very different personalities, but more important is the difference in perspective each brings to his presidential campaign. Specifically, each has a very different diagnosis of the fundamental illness from which America suffers, and for which they are offering themselves as the cure.

That's worth understanding because they differ so little on the vast majority of issues the next president will confront. They all want to outlaw abortion, cut taxes for the wealthy, ignore climate change, increase military spending, and repeal the Affordable Care Act, among many other things. But they are presenting different diagnoses of what ails America, and that question is fundamental to every presidential campaign.

Let's begin with Ted Cruz. For him, the fundamental problem is the "Washington cartel," the people who hold power in the nation's capital and conspire to keep America from meeting its challenges. While he sometimes talks about it in broad terms, the kind of populism Cruz advocates is really centered within the internal politics of the Republican Party. His story is the tea party's story: Feckless, weak Republicans failed to stand up to Barack Obama, allowing all manner of awful things to befall us over the last seven years, and despite the "R" after their names, they're as much to blame as the president for everything that has gone wrong.

Cruz embodies the tea party spirit in a number of ways, most critically their beliefs about goals and tactics. For them, the fight is what's important, not the objective you're supposedly fighting to achieve. Ask Cruz to list his accomplishments and he'll talk about things like "standing up to ObamaCare" — in other words, a fight he waged and lost. And this is the problem with the story Cruz tells: It's one thing to fight your party from the backbench, but if he were president, what powerful force could he rebel against? Barack Obama would be gone, and Republicans in Congress would be in lockstep with his agenda. Indeed, they'd be sending him so many conservative bills that his biggest fight would be against tendonitis in his signing hand.

There's another problem with Cruz's message, which is that it's not just partisan, it's intra-partisan. It depends on its listeners sharing Cruz's contempt for the GOP, not because of what it believes in, but because it hasn't been radically conservative enough.

Now let's turn to Marco Rubio. For him, America's problem can be summed up in two words: Barack Obama. No other Republican has been as relentless in their criticism of Obama as Rubio. He may not be the favorite of conservative talk radio hosts (they're divided between Trump and Cruz), but he's the candidate who talks most like a talk radio host, particularly in his insistence that not only have Obama's policies been disastrous, but this was by design, that Obama is intentionally working to destroy America, or at the very least wound it grievously. In this telling, Obama isn't a terrible president, he's a ruthlessly effective one, carrying out his villainous plan to weaken us in the face of our enemies, outlaw Christianity, steal money from hardworking Americans to reward his legions of shiftless government leeches, and generally turn America into a statist nightmare.

Rubio's commitment to this narrative was on vivid display in the last debate, where he managed to turn every query he got into a motive-questioning attack on Obama within a sentence or two. He summed up his feelings at one point: "This is the greatest country in the history of mankind. But in 2008, we elected a president that didn't want to fix America. He wants to change America. We elected a president that doesn't believe in the Constitution. He undermines it. We elected a president that is weakening America on the global stage. We elected a president that doesn't believe in the free enterprise system. This election has to be about reversing all of that damage."

To any fair-minded person, the idea that Obama has set out on a plan to destroy the country is self-evidently ludicrous, whether you agree with his politics or not. But it's a staple of contemporary right-wing thought, one you can hear on a daily basis on conservative talk radio and read in the ever-expanding library of right-wing screeds that continue to line bookstore shelves. I have no idea whether Marco Rubio actually believes it, but there's no doubt that he has adopted it as the very foundation of his rhetoric. These days, if you asked Rubio what his favorite flavor of ice cream is, he would respond, "Barack Obama wants to turn America into a place where children can't even enjoy ice cream."

Donald Trump, on the other hand, barely mentions Obama or his policies, and doesn't seem to care about whether Mitch McConnell has betrayed the conservative cause. For him, the problem is everywhere at once, a general decline in America's fortunes. We're led by idiots, we don't make anything anymore, the country is a disaster, and above all, we've become losers. When he talks about illegal immigration, the sentence he repeats over and over is "We don't have a country," a weirdly defeated way of describing the supposed porousness of our borders. He effectively taps into feelings of unease with vague expressions of despair; when he describes his plan to exclude Muslims from coming to America, he inevitably says we have to do it "until our leaders can figure out what the hell is going on." If you're confused and distressed, he's your man.

You may have noticed that two out of these three stories are aimed firmly at voters who already know how they'll vote in the fall. It's almost unimaginable that Cruz or Rubio would continue making the same case when they're confronted with the task of appealing to independent voters and even Democrats in order to win a national majority. And that's the biggest weakness in the stories they tell: Unless you already agree with them, you won't buy it. Trump, in contrast, will have a hard time selling his story to anyone who doesn't think America has become a hellhole.

And one of these guys will probably be the Republican nominee for president.