Making his Sunday news shows debut as the Republican vice presidential candidate, Rep. Paul Ryan (Wis.) underscored the importance of closing tax loopholes utilized by the wealthy. But he would not specify which loopholes he and Mitt Romney are willing to close to help pay for a reduction in taxes the GOP ticket is proposing.

Ryan said on ABC's "This Week With George Stephanopoulos" that ending tax loopholes used by high-income earners allows for lower tax rates for the rest of the country.

"Here's the point I'm trying to make here, George," Ryan said. "We think the secret to economic growth is lower tax rates for families and successful small businesses by plugging loopholes."

"Now the question is, not necessarily what loopholes go, but who gets them," Ryan continued. "High-income earners use most of the loopholes.  That means they can shelter their income from taxation."

Stephanopoulos pressed Ryan for specifics. “Don't voters have a right -- to know which loopholes you're going to go after?” he asked.

"So Mitt Romney and I, based on our experience, think the best way to do this is to show the framework, show the outlines of these plans, and then to work with Congress to do this," Ryan said. "That's how you get things done."

Ryan dismissed the idea that the plan is a secret one. "What we don't want is a secret plan," he said, and added: "We want to have this debate in the public. We want to have this debate with Congress. And we want to do this with the consent of the elected representatives of the people and figure out what loopholes should stay or go and who should or should not get them."

Ryan was also asked about a a 10:1 ratio of spending cuts to tax increases that has been rejected by Romney during a GOP presidential debate. Ryan did not outright reject the ratio (nor did he advocate for it) saying, "it depends on the quality of the agreement.  It depends on the quality of the policy. ... what really matters to me is not ratios -- but what matters is the quality of the policy."

Ryan also spoke to Norah O'Donnell on CBS News's "Face The Nation." In that interview, he defended his vote for a deal to increase the debt limit last year that included a provision for automatic cuts in defense spending. In an interview with NBC's "Meet The Press" on Sunday, Romney said it was a mistake for Republicans to go along with the cuts.

"You know why I voted for it? Because I was working to find common ground with Democrats to get a down payment on deficit reduction. I worked with President Obama to find common ground to get a down payment on deficit reduction. It wasn’t a big down payment, but it was a step in the right direction," Ryan said.

Ryan added that he pressed for measures to prevent the defense cuts from taking place. "We passed, in the House, a bill to prevent those devastating defense cuts by cutting spending elsewhere. The Senate’s done nothing. President Obama’s done nothing," he said.

"Well it was interesting to hear Congressman Ryan. I mean, you asked him questions," responded White House senior adviser David Plouffe, who also appeared on "Face The Nation." "He voted for the sequester, he voted for the Budget Control Act."

On foreign policy, Ryan said on CBS that "I think a nuclear Iran is our biggest foreign policy threat today." He also sought to tout his credentials on foreign affairs.

"I’ve been in Congress for 14 years. He [Obama] was in the Senate  for far, far less time than that. I’ve voted – you know, Norah, I’ve voted to send men and women to war," Ryan said. "I’ve been to Iraq and Afghanistan. I’ve met with our troops to get their perspectives. I’ve been to the funerals, I’ve talked to the widows, I’ve talked to the wives, the moms and the dads. That’s something. That matters."