Really, is there anything more amusing in politics today than watching conservatives abandon Mitt Romney at a furious rate because he had the misfortune of passing a health plan with a Republican idea at its core that, unbeknownst to him, Obama would shortly adopt as his own?

Yesterday you had Tea Party chieftain Jim DeMint appearing to signal that he would never endorse the former Massachusetts governor unless he admits Romneycare and the individual mandate were a “colossal mistake.” This, even though DeMint himself cited Romneycare as one of the primary reasons he had decided to endorse Romney’s presidential campaign last time — before Obama embraced the individual mandate.

Now we have another one: Rick Santorum. Earlier this week, the conservative former Pennsylvania senator, who also appears to be running for president, had this to say about how Romneycare should render Mitt a nonstarter for the 2012 GOP nomination:

He called Romney’s health care plan “a failure” and touted himself as a “consistent conservative.”

“We need someone who is a strong, principled conservative who believes not in government mandates, not in government control of the health care system, but in a patient-centered approach to health care,” Santorum said.

According to Santorum, Romney believes in “government control of the health care system.” It doesn’t get dirtier than that. Yet it turns out that Santorum endorsed Romney back in 2008, in the full knowledge that Romney had passed Romneycare. Why? Here’s why:

“Governor Romney is the candidate who will stand up for the conservative principles that we hold dear...Governor Romney has a deep understanding of the important issues confronting our country today, and he is the clear conservative candidate that can go into the general election with a united Republican Party.”

You see, there was a time when conservatives like Jim DeMint hailed Romney as a true conservative precisely because his health care bill was built on what they said were conservative principles. But now that Obama has reinvented the individual mandate as tyranny, conservatives are beating up on Romney and Romneycare as a convenient way to burnish their own conservative cred with the base. Politics just isn’t fair.