For months, likely Republican presidential nominee Mitt Romney has made Barack Obama's supposed "failure of leadership" a centerpiece of his campaign. But like his ill-advised comparison of President Obama to Marie Antoinette, Romney's sound bite could well boomerang. After all, when Multiple Choice Mitt isn't comically reversing his stands, he's too afraid to take any at all.

That cowardice starts with his tax returns. While John Kerry and John McCain at least presented a summary of their (and their well-to-do wives') payments to Uncle Sam, the $250 million Mitt has so far refused to do so. Despite his famous demand in the 1994 Senate race that Ted Kennedy release his tax returns to show he has "nothing to hide," Romney reiterated his own paperwork would not be forthcoming. "We don't have any current plans to release tax returns, but never say never," Romney said, adding:

"I can tell you we follow the tax laws, and if there's an opportunity to save taxes, we like anybody else in this country will follow that opportunity."

Or as he put it to CNN's Wolf Blitzer last week (at around the 6:40 mark):

"I don't put out which tooth paste I use either. It's not that I have something to hide."

That's one interpretation. Another is that Mitt Romney is desperate to avoid the horrible political optics his tax returns would inevitably produce. After all, because Romney's continuing millions in annual income from Bain Capital (a company the Los Angeles Times recently explained "often maximized profits in part by firing workers") are taxed at the 15 percent capital gains rate, Mitt already pays a much lower share to Uncle Sam than most middle class families.

Romney's pusillanimity extends to his own tax proposals as well. Unlike virtually all of his GOP rivals, Romney has held back on endorsing either a flat-tax or the complete elimination of the capital gains tax. As he seemed to suggest to the Wall Street Journal, discretion is the better part of valor when it comes to telling voters about the massive windfall the Romneys would reap under the tax policies that dare not speak their name:

What about his reform principles? Mr. Romney talks only in general terms. "Moving to a consumption-based system is something which is very attractive to me philosophically, but I've not been able to sufficiently model it out to jump on board a consumption-based tax. A flat tax, a true flat tax is also attractive to me. What I like--I mean, I like the simplification of a flat tax. I also like removing the distortion in our tax code for certain classes of investment. And the advantage of a flat tax is getting rid of some of those distortions"...

Amid such generalities, it's hard not to conclude that the candidate is trying to avoid offering any details that might become a political target. And he all but admits as much. "I happen to also recognize," he says, "that if you go out with a tax proposal which conforms to your philosophy but it hasn't been thoroughly analyzed, vetted, put through models and calculated in detail, that you're gonna get hit by the demagogues in the general election."

Mitt Romney's fear of getting hit was also on display during the debt ceiling debate this summer. As the GOP's brinksmanship over defaulting on the U.S. debt reached its climax in late July, Romney turned his tail and fled. As MSNBC reported at the time:

NBC's Garrett Haake reported that Mitt Romney told reporters in Ohio yesterday that he would not comment on the debt negotiations in Washington. And so far, he has refused to either endorse Boehner's legislation (as Huntsman has done) or oppose it (as Pawlenty and Bachman have done). Our question: How does someone who wants to be the leader of the Republican Party not have a position on one of the biggest issues facing Washington, especially after the dueling primetime speeches by Obama and Boehner? It's actually quite surprising; this isn't just another Washington fight. Is the lack of a position proof of how fragile Team Romney believes its front-runner status is right now?

(Ultimately, Romney used Facebook to announce his support of the Boehner bill, but only after it passed the GOP House.)

As it turns out, Ohio was the scene of another of Mitt Romney's moments in cowardice.

After visiting a Republican phone bank calling voters about the state's controversial Issue 2 curbing public unions, Romney amazingly refused to take a position:

"I'm not saying anything one way or the other about the two ballot issues."

Embarrassed by his obvious lack of backbone, Romney endorsed the measure the next day. Ohio voters, who handily defeated the Republican measure, won't soon forget Romney said goodbye to his spine in Columbus.

Romney's vertebra similarly went missing on immigration and abortion, two issues near and dear to the Republican primary voter's heart. As Steve Benen recounted, Mitt's campaign simply would not answer Joe Klein question about what President Romney would do about the 12 million illegal immigrants already in the country:

The evasion wasn't exactly graceful. Klein asked what Romney would do with the undocumented immigrants who are already here, and Fehrnstrom replied, "He would not grant them amnesty." Right, Klein said, but instead of amnesty, what would Romney do with these people? "He would not grant them amnesty," Fehrnstrom answered. Got it, Klein said, but what, specifically, would Romney do? "I just told you, he's not going to grant them amnesty," the campaign spokesperson said. When Klein then explained that this isn't actually an answer, Fehrnstrom, once again, said, "He would not grant them amnesty."

The Romney camp built a similar stonewall after their man seemingly came out in support of the soon-to-be defeated "personhood" initiative in Mississippi. But the day after the ballot measure went down to crushing defeat, Team Romney insisted "he's being falsely characterized as supporting a proposed amendment to define a fertilized egg as a 'person.'"

On matters small and large, duck and cover is Mitt Romney's posture. Afraid to admit that he has obviously been running for President without interruption since his failed campaign four years ago, Romney's wife claimed his 2012 run was all her idea. As Ann Romney told Wolf Blitzer last week (starting around the 2:30 mark in the video above):

BLITZER: Is it true that you had to talk to Mitt into running again?

ANN ROMNEY. ROMNEY: It is true...after the last campaign, it was kind of ironic that I was the one that said I'd never do this again, and now, this time around, I'm saying, you know what, Mitt, you've got to do this again.

But in Mitt's telling, his latest White House bid is all due to Barack Obama. As he told the Wall Street Journal just days ago, Mitt was content to hang out in his $12 million, soon-to-be doubled-in-size California beach side home:

The Republican presidential candidate says he never intended to run for office again after 2008--"I went back and bought a home which was far too expensive and grandiose for the purposes of another campaign," he jokes. He was drawn back into public life amid Mr. Obama's bid to "fundamentally transform" the country, to use the president's own words, into "an entitlement society," to use Mr. Romney's.

Given his Boston area townhouse and lakeside mansion with man-made beach in New Hampshire, a third palatial retreat would have seemed excessive for a candidate Romney. After all, Mitt Romney's running for office as a "man of the people"; he can't have mansions, for Pete's sake.

"If it seems like this keeps coming up with the former governor," Benen concluded, "it's not your imagination."

Romney refused to take a stand on Paul Ryan's budget. Romney refused to take a stand when asked about voters booing a U.S. soldier serving in Iraq during a Republican debate. Romney refused to take a stand when Rick Perry dabbled in Birtherism. Romney initially refused to take a stand on Ohio's campaign to undermine collective-bargaining rights, and then sheepishly backpedaled when the right complained.

There's going to come a point next year when the Obama campaign is likely to say, "Mitt Romney lacks the courage and the character to be a leader." And the criticism will sting because it's based in fact.

And so it goes for the man George Will rightly described as a "recidivist reviser of his principles." On the issues where he doesn't change his mind, Mitt Romney - the man who would be leader of the Free World - lacks "the courage of his absence of convictions."

(This piece also appears at Perrspectives.)