It’s always been a little bizarre to hear Republicans complain that 47 percent of Americans pay no net income taxes. When you see Mitt Romney bemoan this fact, you wonder what he’d prefer — higher taxes on lower incomes?

Unfortunately, Romney hasn’t been forced to answer that question. But Tim Kaine was on Thursday night. In a debate, David Gregory asked Kaine, a Democrat running for Senate in centrist Virginia, whether everyone in the state should be required to pay something in federal income taxes. Kaine said he is “open” to the idea. He stumbled into a trap Republicans had set for themselves.

Republicans then had the gall to attack him for it. “On Tax Hikes,” declared the Republican Party of Virginia, “Tim Kaine Just Can’t Help Himself.”

But neither, apparently, can uber-conservative Michele Bachmann, who made the 47 percent line a keystone of her recent presidential campaign. “That’s why, in my tax plan, I have everyone paying something,” Bachmann said in November, 2011. “Even if it means paying the price of two Happy Meals a year, like $10, everyone can afford to pay at least that.”

Ironically, Kaine on Thursday also explained why Romney, Bachmann’s — and his own — logic is faulty. Many Americans might not pay income tax, but they certainly pay federal payroll, state and local taxes. Many pay more in federal taxes, he pointed out, than Romney has lately. True, analysts say that the basic budget math will require some sort of tax hike on middle-income Americans — but that is a different issue from claiming America’s tax code is so wrong-headedly progressive as to require new taxes on everyone, down to the lowest of earners.