Mike Huckabee's decision marks the end of compassionate conservatism.
This wasn't just one vinegary interview conducted as the party called for him to leave the race. This was a salvo in a war between Huckabee and conservatives personified by the Club for Growth, which had attacked him relentlessly over his Arkansas record. In his memoir Do the Right Thing, published right after the November election, Huckabee warned that libertarians were hijacking the GOP. "The libertarian faux-cons have helped to drive the party even further away from its base of the hard-working middle class," he wrote.
And he kept on saying that, even and especially when libertarians, via the Tea Party movement, took a leading role in the GOP. He skipped the Conservative Political Action Conference in 2010 because it had become "increasingly more libertarian and less Republican over the last years."
What about Huckabee and the Tea Party, anyway? He never headlined a Tea Party event, but he praised the movement. Two months ago, the NBC/Wall Street Journal poll revealed that a plurality of voters who identified with the Tea Party would vote for him. But the Tea Party is vast; it contains multitudes. Huckabee's Tea Party fans aren't libertarians. They're the people who chanted, "Keep your government hands off my Medicare!" They're the ones who are making life trickier for Rep. Paul Ryan right now because they want to bring spending under control but don't want to cut entitlements. And now they don't have a candidate.
They might not have had a candidate even if Huckabee had run. In the last campaign's debates, when asked about tax policy, he'd effectively punt and remind people that he wanted to demolish the IRS and institute a national consumption tax. At the first South Carolina debate, Huckabee implied that he'd only raised taxes because Democrats and voters had forced him to.
Things had changed since then. Huckabee was more popular. His party had drifted further from him on economics. There was a way for Huckabee to challenge that. He didn't take it. He listened to his heart.
Correction, May 17, 2011: This article originally implied that the age of Earth could be ascertained using carbon dating. It is radiometric dating that reveals the age of the planet. (Return to the corrected sentence.)
David Weigel is a Slate political reporter. You can reach him at firstname.lastname@example.org, or tweet at him @daveweigel.
Photograph of Mike Huckabee by Chip Somodevilla/Getty Images.