Of all the attacks Gingrich lobbed at Romney in the final days of the Florida race, the most incendiary may have been the claim that Romney disrespected Catholics’ conscience protections in Massachusetts. He compared Romney’s approach to emergency contraception to Obama’s, which has raised hackles among some in the Catholic community.

“I would like him to respect our religion,” Gingrich told a campaign rally in Tampa.

It was a divisive, explosive attack that evidently got under Romney’s skin. In his remarks on the night of the Florida primary, Romney pledged before a national audience that he would defend “religious liberty” as president – a notable departure from his usual believe-in-America routine.

Gingrich is an imperfect messenger for religious conservatives, but at least temperamentally, he’s a superb spokesman for aggrieved, lower-income whites who may be skeptical of whether either Romney or Obama shares their values.

The more Gingrich tars Romney as one of “them” instead of one of “us,” the uglier the primary campaign will be – and the better a chance Gingrich will have of prevailing against an opponent whose discomfort in talking about both his wealth and his faith make him a remote figure for many Republicans.