The Obama campaign has criticized Romney for not revealing which tax loopholes he would close, and has argued that his proposed reforms would ultimately increase taxes on middle-class families while decreasing obligations for the wealthiest Americans.

"The bigger issue is that he isn’t being straight about his own taxes; the bigger issue is that he isn’t being straight about what he's going to do to everyone else's taxes," Obama adviser David Axelrod said Sunday to ABC News. "You heard [Republican National Committee] Chairman [Reince] Priebus say, 'We have specifics coming out of our eyeballs.' I don’t think anybody else has seen those specifics."

Democrats have said the only way Romney's plan could be deficit-neutral, as has been pledged, would be via the elimination of deductions that also help the middle class. But Ryan indicated Monday that the "premise" of the Republican plan was focusing on tax breaks for the wealthiest Americans.

"Our pro-growth tax reforms are to lower tax rates for everybody by plugging loopholes, starting with people like Mitt Romney," Ryan said.

On Friday, the Romney campaign presented a notarized memo from Romney's accountants attesting that the Romneys averaged an effective federal tax rate of 20.2 percent over the past 20 years and gave an average of 13.45 percent to charity. But Romney would have paid an effective tax rate below 13 percent last year had he taken advantage of all available deductions.

Ryan said the elimination of deductions wouldn't necessarily hurt middle-class families because of economic growth that would raise income and create jobs across the board.

"Revenue-neutral tax reform is what we're talking about, but we believe, if we get these tax rates down, and have a more competitive and simple tax system, that will trigger an economic renaissance," Ryan said. "We think we get about 7 million jobs alone from these pro-growth tax reforms."

Ryan also defended Romney over his "47 percent" comments, secretly recorded at a fundraiser earlier this year.

"Because of the stagnant Obama economy, more able-bodied people are dependent upon the government because they have no opportunities in this economy," Ryan said. "What Mitt and I are trying to do is say here are the ideas to get growth, to get jobs created, so that workers can have job security and higher take-home pay, and here's how you get people from dependency, from welfare dependency, back to work."