Last week Politico reported that, facing falling approval ratings and high unemployment, President Obama’s re-election campaign would go negative on his Republican opponent. Currently that means training their fire on Mitt Romney, the national front runner. “Obama’s re-elect will portray the public Romney as inauthentic, unprincipled and, in a word used repeatedly by Obama’s advisers in about a dozen interviews, “weird,” write Ben Smith and Jonathan Martin.

The inevitable high-minded hand-wringing about the “moral cost” to the Obama campaign ensued, and by Friday morning Obama adviser David Axelrod was disavowing the story, saying he would fire anyone who calls Romney weird.

Hopefully that’s just spin from Axelrod, because the strategy Politico describes is a good one. The same exact line of attack against John Kerry—that he’s an out-of-touch flip-flopper—worked well for George W. Bush in 2004. That’s how Bush managed to win re-election with only a 48 percent approval rating.

Of course, the attack against Kerry was silly. Anyone who has spent a long enough time in politics will have what at least appear to be shifts in position. George W. Bush could have just as fairly been described as a flip-flopping elite as Kerry, but that was hardly the main reason Bush was a bad president.

So what makes Romney’s flip-flopping different? The fact that it exposes not just changes in specific position but rather Romney’s total lack of identity or purpose in politics.

Most politicians adhere to a broad political orientation, such as liberal Democrat or conservative Republican, and shift positions over time as the nature of what it means to hold that place on the spectrum changes. For example, if you are a liberal on social issues you may have flip-flopped over the last decade from opposing to supporting gay marriage, as the realm of what is politically possible has shifted. But there is an underlying constancy in that you are always pushing for social progress.

Romney, on the other hand, has no such identity. In Massachusetts he ran to the left; now he runs far to the right. There is no overarching purpose—whether it be fighting for social justice or defending traditional family values—to his political career.

It is perfectly normal for candidates to recalibrate their stance on a complicated issue such as a war over time, but Romney changes his position on issues like abortion on which there is no change of facts on the ground, only in the office he seeks. And when he makes a reversal he adopts the most extreme iteration of his new stance. So he says the Affordable Care Act, modeled on his own law in Massachusetts, is not only a step too far for the federal government it is “a government takeover of healthcare.” (Politifact labels that claim “flatly incorrect.”)

In 2002 he boasted that “there’s not a paper’s width worth of difference” between his and Democrat Shannon O’Brien’s position on abortion, now he adheres to Republican antiabortion rights orthodoxy and wants a constitutional amendment to ban gay marriage. In 1996 he was so opposed to a flat tax that he took out an ad in the Boston Globe calling it “a tax cut for fat cats.” On Monday he said he wants only one tax bracket.

Romney obviously doesn’t really believe what he now says and it’s not clear if he believed his initial position either. That’s especially true because he does not even bother to come up with a plausible explanation—other than political expediency—as to why he has so radically changed his position.

What one comes away with from watching Romney is that he lacks any core convictions whatsoever. That’s preferable to the ignorance and extremism of his primary opponents. But it is not a positive characteristic. People who got into politics with no sense of what they wish to accomplish other than attaining status and power strike many voters as untrustworthy, and with good reason.

There is nothing underhanded or unfair about Obama’s campaign or supporters pointing this out. It is the flip side of how he would run against Rick Perry or Michele Bachmann, where he would presumably attack their outlandish, if honestly held, positions.

Every election is, or at least should be, a “choice” election rather than a referendum on the incumbent. Voters who went to the polls in 2010 to register their displeasure with deficit spending and slow economic growth by voting Republican acted stupidly. They returned to power the Republicans’ austerity regime and refusal to make a fair deal to reduce the deficit. If they had realized that they were choosing the greater of two evils they might have voted differently. It is not only fair for the Obama campaign to make this choice explicit, it is their democratic duty.

If you want to see just how far Mitt Romney has come from 2002, watch this video his gubernatorial debate with O’Brien.