When you’re a margin-of-error candidate, you spend the majority of the primary debates standing at the end of the row in silence, waiting for the moderators to give you a modicum of attention. So when you get a chance to take a (principled, informed) swipe at the frontrunner, you swing for the fences.

Unless, of course, you’re Jon Huntsman.

Although his campaign has spent the past week firing off aggressive attack ads against Mitt Romney, perhaps sensing an opening to emerge as the field’s pre-eminent anti-Romney candidate, Huntsman proved utterly incapable of landing a blow at Wednesday night’s CNBC debate when the opportunity presented itself. The worst part? The subject was China.

The question at hand was how the candidates planned to deal with China’s emerging status as an economic superpower. Romney, for his part, stuck to some well-crafted talking points by accusing the country of “cheating on almost every dimension,” and proposed implementing a tariff on Chinese exports to punish the country for artificially devaluing its currency.

The moderators then turned to Huntsman, who just months ago had been serving as U.S. ambassador to China. His response was predictably measured and nuanced, explaining that patience would be crucial in developing a long-term relationship with the country. Then he took an ever-so-subtle dig at Romney’s solution.

“You can give applause lines, you can pander,” Huntsman said. “[But] you will start a trade war when you start slapping tariffs on Chinese goods.”

Moderator John Harwood stopped him there: “Are you saying Governor Romney is pandering?”

Huntsman tried to dodge the question, but Harwood interjected again: “He’s standing right here. Is he pandering?”

Looking mildly uncomfortable with a stiff grin on his face, Huntsman responded delicately, “I have said it before, that policy is one of simply pandering.”

It didn’t even take National Review editor Rich Lowry all 140 characters to sum up the exchange on Twitter: “huntsman not exactly a killer on the attack.”

Indeed, for all his campaign’s creative efforts to take down Romney, including the hilariously named new website ScaredMittless2012.com, Huntsman was unable or unwilling to take a jab when it mattered most. It’s one thing to compare Romney to a “perfectly lubricated weathervane” during a softball CNN interview; it’s quite another when he’s standing face to face with the guy on a debate stage. The reality is that Huntsman just might lack the killer instinct to stare down an opponent and say “You’re a shameless panderer” on national TV.

It’s no accident that Huntsman has spent the majority of his public service career in diplomatic positions. By all accounts, he thrives at peacemaking and consensus building, and he possesses an emotional intelligence that enables him to befriend people easily. But personal attacks have never been in his nature.

Indeed, before he even entered the race, Matt David, who now serves as campaign manager, told Politico, “He’s not one to tear anyone down by name, whether that person is Governor Tim Pawlenty, Governor Mitt Romney, or President Barack Obama.”

Of course, if the candidate himself is unwilling to name names, he’s got plenty of staffers around him who are spoiling for a fight. Minutes after Huntsman passed up the chance to call out Romney, campaign spokesman Tim Miller blasted out a sharply worded email to the press.

“Jon Huntsman doesn’t come from the Romney/Trump school of foreign affairs,” Miller wrote. “We need a president who understands China and the complexity of the relationship.”

If only Huntsman had shown some of that feistiness on stage.