On the eve of Tuesday’s Alabama and Mississippi primaries, Newt Gingrich referred to Mitt Romney as a “weak front-runner.”

Romney should have let it go.

Instead, he tried to zing Gingrich back. “If I’m a weak front-runner, what does that make Newt Gingrich?” Romney replied. “Because I’m well ahead of him.”

On Tuesday night, in the primaries where he tried to “close the deal,” Mitt Romney was behind Newt Gingrich. And he was far behind Rick Santorum.

The devastating defeats for Romney on “Southern Tuesday” were made all the more painful by the fact that Mitt tried to do Dixie.

He really did.

“I am learning to say ‘y’all’ and I like grits and things,” the candidate announced on what is likely to be the last trip he will ever make to Pascagoula, Mississippi.

Romney may actually like grits.

But Southern Republicans like authentic conservatives.

And Mitt Romney doesn’t meet the standard.

Romney, who ran to the left of Teddy Kennedy on some issues in a 1994 Massachusetts gubernatorial race, governed that state as a moderate and now is trying to position himself as an Obama-hating, union-bashing cultural warrior who has got all the authenticity of a Lynyrd Skynyrd cover band trying to bang out a version of “Freebird.”

Sometimes, it just doesn’t work.

And it certainly didn’t work on Southern Tuesday, the primary day when Romney was supposed to finally “close the deal.”

All the sometimes Republican front-runner needed to do, after two-and-a-half arduous months of having to fend off challengers who were supposed to be footnotes in “The Making of the President: 2012,” was win a couple of Southern states.

But he couldn’t do it.

He couldn’t even come in second.

In Alabama and in Mississippi, states where he had most of the money, most of the establishment endorsements and (we were told) most of the momentum, Romney a weak third behind a resurgent Santorum and a resilient Gingrich.

It was a dismal night for Mitt.

In two of the most Republican states in the union, the man who wants to lead the Republican Party in what is a definitional presidential race this fall was opposed by more than 70 percent of Republicans.

That maintained a pattern of Southern primary finishes where Romney could not break 30 percent. (Yes, Mitt did win two states of the former Confederacy, Virginia and Florida, but in each case he was saved by transplanted Yankees—carrying the most culturally and politically “northern” parts of those Southern states.)

If Romney just had a Southern problem, that would be one thing. But, of course, the one thing that unites Republicans in virtually every region of the country is their disdain for Mitt Romney.

Seventy-five percent of Iowa Republican caucus voters opposed Mitt, and that wasn’t the worst of it. In Minnesota, 82 percent of Republican caucus-goers rejected Romney. Even where he won, as in the battleground states of Michigan and Ohio, it was by narrow margins against a divided opposition.

There are Republican strategists who think that “Obama Hate"—a condition characterized by excessive Fox News consumption—will allow any Republican nominee to unite the party for the fall fight with the president.

Perhaps.

But the same authenticity deficit that tripped Mitt up in the very Republican states of Mississippi and Alabama—and South Carolina, and Georgia and so on—is going to keep tripping him up Illinois (where polls put Romney and Santorum in a statistical dead heat), Pennsylvania (where Santorum is way ahead) and beyond.

Romney wanted so badly to close the deal in Alabama and Mississippi that he rendered himself ridiculous with all that talk of grits and “y’alls.”

But he did not close any deal. He just confirmed his absurdity. And his inability to beat a washed-up former senator from Pennsylvania and the disgraced former speaker of the US House of Representatives means that he will be performing in the theater of the absurd that the Republican primaries have become for weeks, perhaps months, to come.

John Nichols’s new book on protests and politics is Uprising: How Wisconsin Renewed the Politics of Protest, from Madison to Wall Street, just out from Nation Books. Follow John Nichols on Twitter @NicholsUprising