 -- Stumping for votes in the pivotal battleground of Ohio, President Barack Obama hammered Mitt Romney's tax plan on Wednesday, highlighting a new study that said the Republican challenger's blueprint could leave poor and middle-class Americans paying more to the IRS to offset tax cuts for the wealthiest.

"If Gov. Romney wants to keep his word and pay for this plan, then he'd have to cut tax breaks that middle-class families depend on to pay for your home, the home mortgage deduction; to pay for your health care, the health care deduction; (or) to send your kids to college," the president said.

"And here's the thing: He's not asking you to contribute more to pay down the deficit, he's not asking you to pay more to invest in our children's education, or rebuild our roads or put more folks back to work," Obama said in Mansfield, Ohio. "He's asking you to pay more so that people like him can get a big tax cut."

Obama was referring to a new independent study by the Brookings Institution think tank and the Tax Policy Center that found Romney's tax plan would leave millionaires paying less in taxes and the poor and middle class paying more. (One of the study's authors is a former member of Obama's Council of Economic Advisers). The former Massachusetts governor has called for extending the tax cuts first championed by President George W. Bush in 2001 and 2003 and extended by Obama in late 2010. His approach would also reduce rates an additional 20 percent, and abolish taxes on investment for Americans making under $200,000. But his blueprint is notably vague on how it would avoid expanding the deficit.

The study found that the Republican candidate's proposal would leave incomes of Americans who make more than $1 million per year $87,000 higher after taxes, those making between $500,000 and $1 million would get a $17,000 tax cut, those making between $200,000 and $500,000 would get $1,800, while households below that income level would see their tax bill rise by $500 on average.

"It is not mathematically possible to design a revenue-neutral plan that preserves current incentives for savings and investment and that does not result in a net tax cut for high- income taxpayers and a net tax increase for lower- and/or middle-income taxpayers under the assumptions we have described above," the study's authors wrote.

Romney's proposals would cut federal revenues by $360 billion in 2015, and the Republican's pledge not to widen the deficit "would require deep reductions in many popular tax benefits ranging from the mortgage interest deduction, the exclusion for employer-provided health insurance, the deduction for charitable contributions, and benefits for low- and middle-income families and children like the EITC (Earned Income Tax Credit) and child tax credit."

Republicans often say that more money in the pockets of higher-income Americans means more investment, which means more jobs, and therefore more income—suggesting that a tax cut could in theory partly pay for itself.

But the study crunched the numbers and reported that "even generous assumptions regarding the ability of tax cuts to partially pay for themselves does not change the basic qualitative results."

Obama's trip to Ohio also highlighted a local controversy. Buckeye State media reported that Air Force One landed at an air base set to be shuttered under the president's proposed cuts in defense spending.