President Obama painted Mitt Romney's tax plan as a "sketchy deal" during Tuesday night's debate and accused the Republican nominee of being fuzzy on the math.
Obama said Romney's tax plan, when combined with vows to increase military spending and maintain the Bush-era tax rates for the wealthy, doesn't add up.
"If somebody came to you, governor, with a plan that said, 'Here, I want to spend seven or eight trillion dollars, and we're going to pay for it, but we can't tell you until maybe after the election how we're going to do it,' you wouldn't have taken such a sketchy deal, and neither should you, the American people," he said.
The Obama campaign contends Romney's plan is not mathematically possible, and the president attacked Romney for not specifying what deductions and credits he would eliminate to cover the cost of lowering rates.
"We haven't heard from the governor any specifics beyond Big Bird and eliminating funding for Planned Parenthood in terms of how he pays for that," he said.
Obama's also jabbed at the GOP nominee's tax rate, which is around 15 percent because most of his income comes from investments, which are taxed at a different rate than income.
"The fact that he only has to pay 14 percent on his taxes when a lot of you are paying much higher, he's already taken that off the board. Capital gains are going to continue at a low rate," Obama said.
Romney rebutted forcefully, calling the president's characterization "completely foreign" to his actual plan.
"Of course they add up. I was someone who ran businesses for 25 years," he said, referring to his time at the private-equity firm Bain Capital.
Romney declined to name what specifics deductions would be cut under his plan, but suggested he would consider setting a cap on the deductions taxpayers can claim.
"One way to do that gets, I'm going to pick a number, $25,000 worth of credits, and you can decide which ones to use," he said.
Romney had previously suggested that he would consider a $17,000 cap on deductions, which again would set a limit on the amount of deductions a person could take without specifically banning any particular credit.
He also said that he planned to eliminate taxes on interest, dividends and capital gains for anyone making $200,000 a year or less.
"I want to get some relief to middle-income families," he said.