Before every recent debate for the Republican presidential candidates, I think to myself, “OK, this will finally be the one in which the GOP field goes after Mitt Romney.” And after every debate, I think to myself, “Do these guys not understand how this game works?”

Last night’s gathering in New Hampshire was supposed to provide all kinds of fireworks. With time running out, and opportunities dwindling, Rick Santorum, Newt Gingrich, Ron Paul, Rick Perry, and Jon Huntsman would have no choice but to make the case why Romney is the wrong man for the job.

Except they did have a choice — they could just throw a few mild jabs and let the Romney coronation continue.

Gingrich and former Pennsylvania Sen. Rick Santorum — who battled Romney to a virtual draw in last week’s Iowa caucuses — offered relatively tepid criticisms of Romney about three quarters of the way through the debate, but had otherwise held off heavy criticism of Romney.

“I do think there’s a difference between a bold Reagan conservative model and a more establishment model that is a little more cautious about taking the kind of changes we need,” Gingrich said in comparing his jobs plan against the former Massachusetts governor’s.

“I don’t think Governor Romney’s plan is particularly bold, or is particularly focused on where the problems are in this country,” Santorum said.

Hmm. Gingrich spent the week breathing fire whenever Romney’s name came up, but when offered an opportunity to contrast his vision with the former governor, the disgraced former House Speaker came up with “a little more cautious.” Santorum, eager to make this a two-person race, threw the “not particularly bold” punch.

You’ve got to be kidding me.

John Dickerson’s reaction was spot-on.

The Romney campaign has the best voodoo operation in American campaign history. This is the only conclusion I can draw after yet another debate in which the front-runner went unscathed. Before the Saturday night debate in Manchester, N.H., Romney’s opponents promised they were going to attack him. They had an opportunity, and they didn’t take it. This has happened repeatedly throughout the GOP primary season. In some room at the Radisson, aides in Romney fleeces and headdresses must have been controlling things with little dolls.

I’m at a loss in trying to explain this. It’s not as if there’s nothing to criticize Romney over. The guy used to support abortion rights, gay rights, gun control, “amnesty” for undocumented immigrants, and combating climate change. He distanced himself from Reagan, attended Planned Parenthood fundraisers, and helped create the blueprint for the Affordable Care Act. He supported taxpayer-funded abortions and taxpayer-financed medical care for undocumented immigrants.

Do these non-Romney candidates not realize they’re losing? Are they reluctant to go after him because they want to be his running mate?

At this point, I’m tempted to think the GOP field is just going through the motions, after having decided a long time ago to just let Romney win the nomination.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.