An increasingly popular argument in conservative circles is that not enough Americans pay income taxes. In last night’s debate, Brian Williams, to his credit, posed the question to Mitt Romney: “[Y]ou often hear this figure, 47% of Americans pay no federal income tax…. Isn’t some of this argument semantics? And won’t the effort to correct that be a de facto tax increase?” The former governor’s response was pretty interesting.

Visit for breaking news, world news, and news about the economy

For those who can’t watch clips online, the first part of Romney’s answer was that he has “a bit of a hard time with the idea that there are people who don’t feel like they’re supporting our troops by contributing tax revenue.” He added, “I don’t want to raise taxes on the American people, but I think everybody ought to feel that they’re part of this effort and that they’re providing for our military, providing for our roads, providing for our schools.”

If I’m the Perry campaign, I’d plan to make great use out of the line, “I don’t want to raise taxes on the American people, but…”

Whether Romney wants to admit it or not, he’s effectively calling for higher middle-class taxes. Indeed, Romney is apparently eager to correct what he sees as a problem, going so far as to argue that lower-income earners “don’t feel like they’re supporting our troops.” Really? They don’t? How would Romney, a multi-millionaire, know how these families feel about supporting the military, which includes many volunteers from working-class communities?

In case anyone’s forgotten, the relevant details matters here: millions of Americans may be exempt from income taxes, but they still pay sales taxes, state taxes, local taxes, Social Security taxes, Medicare/Medicaid taxes, and in many instances, property taxes. It’s not as if these folks are getting away with something — the existing tax structure leaves them out of the income tax system because they don’t make enough money to qualify. Indeed, many are retirees.

Romney has “a hard time with the idea” that these folks end up owing nothing in income taxes. If Romney’s the nominee, expect the Obama campaign to take advantage of this.

As for the second part of Romney’s answer, he boasted that he’ll look out for the middle class by allowing those “earning $200,000 a year and less ought to be able to save their money tax-free, no tax on interest, dividends, or capital gains.” And how much would that benefit the average, middle-income earner? About $70 a year. No, that’s not a typo. Romney wants to give massive tax breaks to the wealthy and corporations, but his idea of boosting the middle class is a tax break that hardly matters at all.

That Romney was the smartest, smoothest candidate on the stage last night is more a condemnation of the GOP field than praise for the former Massachusetts governor.

Our ideas can save democracy... But we need your help! Donate Now!

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.