Republicans watching in dismay as Donald Trump continues to lead their presidential primary contest have almost given up trying to come up with a plan to stop him, with the spreading realization that he'll rise or fall and there's little they can do to affect that outcome. But if you can't change things, at least you can explain them, which leads to the pressing question: Whose fault is this?

Liberals have their answer. Trump, they say, is the culmination of the last seven years of Republican politics, or maybe even the last 50 years. Faced with an angry Tea Party base, the party's leadership encouraged that anger, yet couldn't deliver on any of the substantive promises they made. They told their voters to hate Washington, despise Barack Obama, and fear immigrants — and this is what they got. Go even farther back and you can find Trump's roots in the "Southern Strategy" that worked so well for so long, where Republicans fed working-class whites a diet of racial resentment to get them to sign on with an agenda that served the interests of the wealthy.

As you might imagine, this story isn't particularly appealing to conservatives. So they have a different answer, one which is now gaining increasing currency on the right. Who's to blame for Donald Trump? Why the same man who's to blame for everything that goes wrong in America: Barack Obama.

If Trump gets the nomination, Fox News star Bill O'Reilly tells his viewers, "he should send Barack Obama a very nice gift for making that possible." You see, Obama's unwillingness to keep Americans safe from terrorism and the fact that "he continues to allow people to illegally enter America with impunity" has filled Americans with so much rage that they have turned to the candidate most willing to share it. The brain trust on Fox & Friends agreed that it's only because Obama so obviously doesn't care about America that "when Donald Trump comes out with something that seems extreme, then people say, 'Okay, at least I can say he's looking out for you.'"

Writing in the National Review, Victor Davis Hanson insists that Trump's rise is a response to Barack Obama's unserious leadership, taking selfies and making Final Four picks while the world burns. "It is no accident that President Obama's America has given rise to Donald Trump," writes Ben Domenech. "It is an America that is more tribalist, where people feel more racially and religiously divided; more politically correct, where people feel less free to speak their minds; and it is an America where trust in the nation’s elites, whose skills are credentialed but unproven, are at historic lows." The Wall Street Journal editorial page intoned, "President Obama's insistent failure to confront the realities of global jihad has produced its opposite in Donald Trump's unfiltered nationalist id. This is a reminder of how much damage a misguided American president can do to the country's political culture."

This is a familiar story — when confronted with their own excesses, conservatives cry, "Obama made us be this way!" For instance, any conservative in good standing will tell you that Obama is the most divisive president in American history, ruthlessly pitting Americans against each other for political gain. Of course, when you look at the evidence they offer for this claim, the best they can come up with is standard politics. He says that his opponents are wrong about policy matters! He sometimes even questions their motives, like saying they just want tax cuts for the rich! Appalling.

It's true that in many ways the nation is more divided since Obama became president, but blaming him for that is a little like blaming you for rising rates of burglary because someone broke into your house. We're talking about a president whose opponents regularly call him a secret Muslim communist who is literally trying to destroy America — and I don't mean Joe Biden "literally," I mean literally literally. You can't listen to conservative talk radio for 10 minutes without hearing that Obama wants to bring the country to its knees as part of some black nationalist plan to punish innocent white people for sins they never committed. The man had to show his birth certificate to prove to his opponents that he's actually an American. But he's the one who's "divisive."

If Trump's success is a reaction to Barack Obama, it's only insofar as he's an exaggerated version of the way all Republicans have felt, spoken, and acted toward this president over his entire presidency. Trump's voters didn't wake up a month or two ago and decide that they're nativists attracted to someone offering easy answers to complex problems. They're exactly the voters that the Republican Party has been cultivating, full of fear and anger and contempt. It's just that the party itself was incapable of offering them a compelling embodiment of those feelings, so they turned to an outsider.

And now, after tiptoeing around Trump for months lest they upset those voters, Republicans have finally said that Trump is going too far in his xenophobia and bigotry. If their protestations are too little and too late, they can't pin the blame on Barack Obama. They sowed this poisonous field, and the Trump candidacy is what grew out of it. If it means they lose the White House again because of it — whether Trump is the nominee or not — they'll have no one to blame but themselves.