Of course, some of Romney’s adversaries just don’t have the money to wage an air campaign. But some do. Rick Perry, for instance, has spent more on ads than any other contender in Iowa and also has a super-PAC raising money on his behalf. But Perry has spent his time fighting to be the anti-Romney, not fighting Romney himself.

“We’re battling for conservative support with Gingrich, Santorum, Bachmann and Paul,” says an aide to the Texas governor. “Romney voters are much more liberal.” In the last few days, rather than beating up on Romney, Perry has attacked Santorum and other potential anti-Romneys. “Our TV ads lump all of the congressional insiders together and discuss their collective legacy of earmarks, debt, and Washington excess,” says the aide.

In essence, it’s a fight for second place, and when the campaign is over and the post-mortems begin, it will likely be seen as the second tier’s big mistake. If voters are looking for the best alternative to Romney, they probably want to identify the candidate who can make the best case against Romney. Yet the potential anti-Romneys spent their time attacking each other. In the end, they didn’t help themselves and they let Romney off scot-free.

And what an opportunity they had.