Pretty sure Rick Santorum and Mitt Romney won’t be friends by the end of this. After Romney reminded Santorum in the GOP debate Wednesday that the former Pennsylvania senator endorsed him in the 2008 presidential election, Santorum took to Fox News to completely disavow the endorsement:

“As far as my endorsement, you know what? Fool me once, shame on you. Fool me twice, shame on me. I supported Mitt Romney when it was down to Romney and McCain,” Santorum said on Fox News. “I knew John McCain, I knew what kind of conservative he would be so I landed with Romney. He proved me wrong. He went out right after the campaign was over and he endorsed the Wall Street bailout, he was for big government programs there.”

Santorum is far from alone. Many of those who hailed Mitt Romney as the conservative alternative to John McCain in 2008 have been less than impressed with him this time around. Ann Coulter might be the only Romney soldier still standing — and she’s clearly not happy about it, as in her latest column she called out a couple of Romney’s former supporters for their unflinching reinvestigation of him this time around:

The No. 1 conservative talk-radio host in America, Rush Limbaugh, is critical of Romney, and another top conservative talk-radio host, Mark Levin, is adamantly against Romney — though both Limbaugh and Levin supported Romney as the conservative alternative to John McCain in 2008, and Romney has only gotten better since then.

(Incidentally, Coulter doesn’t offer any particular evidence for her claim that “Romney has only gotten better since then.” How? By supporting the Wall Street bailouts, as Santorum pointed out? By becoming so poised that he’s oblivious to any misconceptions of him and unconcerned to correct them? While I don’t yet want to rule out Romney as a potentially effective GOP nominee, I don’t see that he’s gotten “better” since 2008 — but I think the conservative movement has.)

Mitt Romney might be the single best evidence that the GOP and the conservative movement have changed considerably since 2008. He hasn’t changed, but the support for him has. In 2008, the Tea Party hadn’t yet appeared on the scene. Perhaps Limbaugh, Levin and other prominent conservatives who once supported Romney but now demand better make that demand because, with increased involvement and more outspoken support from conservatives who were once part of “the silent majority,” better actually seems possible.