Vice presidential debate moderator Martha Raddatz gave voice to the frustration of millions when she pressed Rep. Paul Ryan for the details of the tax plan he and Republican presidential nominee Mitt Romney are proposing. The plan calls for keeping all the George W. Bush tax cuts in place, plus cutting individual income tax rates by an additional 20 percent, all supposedly without adding to the deficit.

Let's talk about this 20 percent," Raddatz said. "You have refused yet again to offer specifics on how you pay for that 20 percent across-the-board tax cut. Do you actually have the specifics, or are you still working on it, and that's why you won't tell voters?"

Romney and Ryan say they would accomplish their prodigious feat by reducing tax deductions and loopholes used by the rich and through the stimulus effect of tax cuts have on economic growth. What the nominee and his running mate won't identify is which loopholes they'd close or how they would reduce deductions. They know their numbers won't add up unless their proposed changes include eliminating popular deductions for things like the interest charged on mortgages and student loans and deductions for state and local taxes.

When the nonpartisan Tax Policy Center analyzed the Romney/Ryan plan, it concluded that it was impossible to lower rates that much in a revenue-neutral way solely through measures that target the wealthy. Instead, the center concluded, the across-the-board tax cuts would have to increase the burden on the middle class while providing a tax bonanza for the well-off. People who make $1 million or more per year would see an average tax cut of more than $256,000, the center concluded.