That is Jonathan Alter’s argument:

Gingrich’s primary trajectory will probably resemble that of Jerry Brown, who won a string of late primaries against Jimmy Carter in 1976 and harassed Bill Clinton for months in 1992. (Brown even used a debate to accuse Clinton of funneling money to his wife’s law firm.) In each case, Brown’s challenge from the left made the presumptive Democratic nominee seem more stable and moderate, which helped Carter and later Clinton to victory in November.

Gingrich is now poised to do the same to Romney from the right. His message is that he’s the true Tea Party conservative and Romney is a “Massachusetts moderate.”

Alter goes on to make a number of claims I don’t find convincing, but his Gingrich-as-Brown scenario is an intriguing one. The problem with it, however, is that Brown had a fairly interesting campaign platform, e.g., he called for a single-rate income tax and a VAT, which was an interesting move for a left-of-center candidate. I’m not sure Gingrich deserves much credit on this front.