What, after all, are those strengths? Romney is thought to be well positioned as a candidate who can plausibly offer a different economic path from Obama’s. But that is now Rick Perry’s calling card, buttressed by a job creation record in Texas that Romney cannot match with any equivalent numbers in Massachusetts. And is Romney obviously more electable than other candidates? That, too, isn’t clear, as illustrated by the latest Gallup poll showing remarkably little differences in the performance of Romney, Perry, Paul, and Bachmann against the incumbent. Romney can raise a lot of money, but hasn’t shown so far that he can raise more than any of the other champion money-grubbers in the field. And while Mitt can try to make a more aggressively positive case for his candidacy, no one really believes that he can get excited conservative voters who dominate early contests snake dancing to the polls to put him over the top against carnivorous rivals like Perry and Bachmann. Romney is, at the very best, the New Nixon of the 2012 field—acceptable, but by no means lovable.

So at some point, and some time soon, Mitt Romney is going to have to begin making not only a more positive case for his candidacy but a comparative case by way of attacking his rivals. Bachmann and Perry are highly vulnerable to such attacks, but it’s not clear how well conservatives will react if it’s Romney making the case that the Minnesotan’s wacky religious views are beyond the pale, or that the Texan’s contempt for Social Security is a problem.