A $17,000 cap would result in tax increases on many middle-class people who itemize their tax returns, have expensive health insurance plans, big health care bills or sizeable mortgages. It could also result in tax increases on people such as Romney, who has cut his tax bill significantly by making millions of dollars in charitable contributions.
The Romney camp also pointed to an American Enterprise Institute blog post suggesting that it is possible to cut tax rates by 20 percent across the board without shifting the overall tax burden to the middle class. The Tax Policy Center has repeatedly calculated that there is no way Romney's plan could do so, even if the highest earners lost all of their tax deductions.
The AEI blog post suggested economic growth could make up the lost revenue and argued that Romney's plan to eliminate tax increases under the health care law should not be counted as part of any analysis.
Sununu dismissed the Tax Policy Center analysis as "absolutely wrong."
The Obama campaign continues to press the issue and hammer Romney's own finances, which include millions of dollars in overseas investments.
Obama spokeswoman Jen Psaki told reporters that Romney should have to answer questions about his overseas investments during the debate. And Psaki also highlighted a report by the Commonwealth Fund that 72 million people would be uninsured under Romney's proposals.
"Basically, his slogan is 'Make things worse for health care across America,'" Psaki said.
Psaki also dinged Romney for saying he would not deport illegal immigrants brought here as children who have bought work visas under a program Obama announced several months ago. Romney had repeatedly ducked the issue in recent months, and Psaki said Romney's position remains confusing.
"Does he still believe the Arizona law is a model for comprehensive immigration reform?" she asked.
The immigration issue has helped Obama open up a huge lead on Romney among Hispanic voters.
Former Sen. Scott Brown, R-Mass., candidate for U.S. Senate in New Hampshire, holds his hand over his heart during the singing of the national anthem as he waits to take the stage for his town hall campaign rally with Sen. John McCain at the Pinkerton Academy in Derry, N.H., on Monday, Aug. 18, 2014.