This telling exchange struck me right away during last night’s Follies, but I couldn’t figure out exactly how to present it. Tom Junod had no such problem:

The double knockout came about halfway through the debate, when, as Charlie points out, the combatants were both obviously exhausted, and sick of looking at one another. Romney had been on the attack; Gingrich had responded with customary afflatus, and was now hectoring Romney and the audience about his own flat-tax plan. As it turns out, Gingrich doesn’t want Romney to pay more taxes; he wants everybody else to pay what Romney pays, according to what he called “the Hong Kong model” as a way of reminding us that he’s, you know, smart. And then, as a way of reminding us that he’s you know, quick on his feet, he said, “I’m prepared to describe my flat tax as the Mitt Romney flat tax.”

That’s when it happened. As Gingrich swung, so did Romney. “Do you tax capital gains at 15 percent or zero percent?” he asked.

“Zero,” Newt answered.

“Under that plan, I’d have paid no taxes in the last two years,” Romney said, and with that, despite the tepid nature of the exchange… both men went down. The affably repellent met the repellently affable, and both of them lay stretched out on the canvas.

They had both lowered their guard, you see. Newt, in trying to show himself clever, had revealed that if elected he’s going to make sure that guys like Mitt Romney don’t pay any taxes at all. Mitt, in trying to provoke a reaction against the idea of a guy like him paying no taxes at all, revealed that, well, he’s a guy like Mitt Romney. And so who do you vote for — the guy whose tax plan is going to allow guys like Mitt Romney to get away with paying nothing on the $21.2 million they make each year on their “investments,” or the guy smiling like an executive who gets a kick out of farting in the elevator because he knows no one will say anything?

Neither of them, that’s who, and that’s how both of them managed to choreograph a simultaneous fall straight out of the Sylvester Stallone fantasy factory, the one difference being that no one in his right mind could be rooting for either of them to get up. Least of all the president.

It’s easy to think that there’s nothing at stake, but here were the two leading contenders for Obama’s belt, both uncomfortable in making the mistake of showing exactly what was at stake: the prospect of a guy like Mitt Romney paying even less in taxes than he already does.