There are a couple of sites devoted to tracking Mitt Romney’s flip-flops — Multiple Choice Mitt and Which Mitt both have accurate and worthwhile content — but those responsible for keeping these projects up to date should expect to put in some long hours in the coming months. The former governor just can’t seem to help himself.

As several leading Republican presidential candidates embrace a flat tax as a core campaign position, one contender stands out in not doing so: Mitt Romney, who has a long record of criticizing such plans and famously derided Steve Forbes’s 1996 proposal as a “tax cut for fat cats.”

Lately, though, his tone has been more positive. “I love a flat tax,” he said in August.

Flat-tax plans have come and gone before, and analysts note that they have tended to lose support once they come under scrutiny. But Mr. Romney’s support of the concept of a flat tax underscores the tightrope he is walking as taxes become a larger focus of the Republican presidential race and he faces rivals’ accusations of inconsistency on the issues.

For the record, I agree wholeheartedly with Romney — 1996 version — about the merits of the policy he now loves. A flat tax is a terrible, regressive idea.

But it’s that bigger picture of Romney that continues to amaze. “His problem is that people don’t have confidence that they know what he believes in, and I think there is a pretty good reason for that,” said Chris Chocola, president of the right-wing Club for Growth.

Again, there’s nothing inherently offensive about a political figure changing his or her mind once in a while. Policy makers come to one conclusion, they gain more information, and then they reach a different conclusion.

But this only works when there are sincere changes of heart. It’s something else entirely when pandering politicians reinvent themselves, sometimes more than once, as part of a cynical, calculated ploy. This isn’t indicative of an open mind; it’s evidence of a character flaw.

Romney would have voters believe that he’s simply adapted to changing facts. The circumstances make this impossible to believe — his radical transformations, purely by happenstance, just happen to coincide with political expediency to further Romney’s ambitions? The parallels between his metamorphoses and the shifting political winds are an accident?

Please. Timothy Noah recently did some research to find if Romney had any — literally, any — core and unshakable beliefs that he’s maintained throughout his career. The only one? The fact that Romney wants to be president. Everything else, including every position on every issue, was optional.

The result is a shameless, craven politician who’s flip-flopped like no other American politician in a generation.

I’m perfectly comfortable with a politician pondering doubts and questioning whether he or she is right about an issue. But when a politician changes his views so fundamentally that he’s adopted several different worldviews in a fairly brief time span, is it really unreasonable to question the man’s integrity?

Romney boasted last month, “I stand by my positions. I’m proud of them.” Given Romney’s record of abandoning every policy position he’s ever taken, it was among the most ridiculous political claims I’ve ever heard.

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.