Any minute now, former Massachusetts Gov. Mitt Romney (R) will stand on a New Hampshire stage and launch his second presidential campaign, following a third-place finish in 2008. He’ll have a hard-hitting message to share, which we certainly haven’t heard from Romney before.

According to advance copies of his remarks, Romney will argue that the United States is “only inches away” from abandoning capitalism; we must repeal the federal health care law shaped on his own state plan; and if elected, Romney will “insist” that federal officials “respect the Constitution, including the 10th Amendment.”

This bears no resemblance to previous iterations of Mitt Romney. NBC’s First Read had a good take on this.

Four years ago, it was in Michigan (his original home state), where the backdrop consisted of automotive innovations (and where he walked out to Billy Ocean’s “Get Outta My Dreams, Get Into My Car”). This time, it’s at a picnic/barbeque in New Hampshire (what’s become an adopted home state). Four years ago, Romney was wearing a suit and a tie. This time, he’ll likely keep his more casual look. And four years ago, the message was heavy on social conservatism (stressing the importance of family, the sanctity of human life, and securing the borders). This time, it will be about his background and Barack Obama.

Here’s Romney’s biggest question, and it’s bigger than the individual mandate: Who, exactly, is Romney?

After watching Romney for quite a while, I haven’t the foggiest idea. The best answer I can come up with is Romney’s the guy with no real core beliefs, no unyielding convictions, and a willingness to flip-flop like no other American politician in a generation.

I’ve almost lost count of Romney’s iterations. Romney 1.0 was an independent who distanced himself from Reagan and H.W. Bush. Romney 2.0 was a moderate Republican who passed health care reform. Romney 3.0 was a social conservative who cared deeply about the culture war. Romney 4.0 hysterically fears the death of capitalism and is excited about the 10th Amendment.

Who, exactly, is Romney? No one knows, not even Romney. He’s the first modern presidential candidate to change his fundamental identity several times, depending on which way he thinks the political winds are blowing.

Mitt Romney is like a box of chocolates — you never know what you’re going to get.

That may not, however, derail his candidacy. Indeed, given the rest of the field, Romney is arguably the frontrunner for the GOP nomination. The question is whether he can maintain that status for long.

In fact, it’s pretty easy to imagine the GOP base turning on him. His Republican rivals — likely to gang up on him from the outset — probably look at Romney like a pinata waiting to get hit.

After all, we’re talking about a former pro-choice governor who supported gay rights, gun control, comprehensive immigration reform, and combating climate change, who distanced himself from Reagan, who loves health care mandates, and who attended Planned Parenthood fundraisers.

Worse, his sole gubernatorial accomplishment served as a blueprint for President Obama’s health care policy, a detail the GOP base probably won’t care for when they see it mentioned in attack ads.

As for job creation, apparently the new focus of his campaign, during Romney’s only service in public office, his state’s record on job creation was “one of the worst in the country.” Adding insult to injury, “By the end of his four years in office, Massachusetts had squeezed out a net gain in payroll jobs of just 1 percent, compared with job growth of 5.3 percent for the nation as a whole.”

How bad is Romney’s record? During his tenure, Massachusetts ranked 47th out of 50 states in jobs growth.

But wait, Romney’s defenders say. Sure, his only experience in public office was a bust, but let’s not forget he was also in the private sector, running Bain Capital. Except, that’s not much of a defense given the frequency with which Bain slashed American jobs.

All told, I can see why Romney is the arguable favorite — he has high name recognition, a lot of money, and a credible operation — but I can also see why no one in either party is necessarily afraid of him.

Steve Benen

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.