Romney's comment, made in May, surfaced in a secretly recorded video first publicized Sept. 17 by Mother Jones magazine.
Ryan also said that, in the Oct. 11 debate he will have with Vice President Joe Biden and the three Romney will have during the month with Obama, the Republican ticket will offer voters "a very clear choice" on issues including the economy.
Asked by "Fox News Sunday" host Chris Wallace about recent polls showing Romney trailing Obama, Ryan said the Republican ticket is "running against an incumbent president with incredible resources."
Still, the Wisconsin Republican said, "We are going to win this race."
Romney will turn the race with Obama "upside down" with his performance in their debate this week, New Jersey Governor Chris Christie said on CBS's "Face the Nation"
"He's had a tough couple of weeks, let's be honest," said Christie, who gave the keynote address at the Republican convention. Yet the morning after the Oct. 3 debate in Denver, "you are all going to be scratching your heads, saying, 'Wow, we have a barn-burner now,'" Christie said.
Christie said the debates will give Romney a chance to talk directly to voters nationwide without "being filtered by anybody." He also said Romney performed well in the debates during the Republican primaries.
First Debate's Importance
Ryan played down the importance of the first debate in the Fox interview, saying, "I don't think any one event is going to make or break this campaign."
Obama travels today to the swing state of Nevada, where he'll hold a rally in Las Vegas before settling down in nearby Henderson for practice sessions before the first debate. Romney is in Boston today, with no public events scheduled, as he prepares for his encounter with Obama.
Ohio Senator Rob Portman, a Republican, is playing the role of Obama in Romney's practice sessions, while Massachusetts Senator John Kerry, a former Democratic presidential candidate, is playing Romney for Obama.
The two also will meet in debates on Oct. 16 and Oct. 22.
Romney must make two separate pitches during the debates, Newt Gingrich, the former U.S. House speaker who sought this year's Republican presidential nomination, said on CBS's "Face the Nation" today.
"You first have to make sure people say Obama's stagnation is unacceptable," and then make the case for what a Romney approach would be, Gingrich said. Romney "doesn't have to hit a home run, but Romney has to be at the end of the debate Wednesday night a clear alternative," he said.
Some Democrats on today's television talk programs said Obama's lead in the polls will shrink after the debate because the former Massachusetts governor will get a boost from being on the same stage as the president.
"This race is going to tighten," David Plouffe, a senior adviser to Obama, said on NBC's "Meet the Press." On ABC's "This Week," Plouffe said, "We believed all along that Governor Romney probably has more benefit out of this debate potentially than we do."
Former Pennsylvania Governor Ed Rendell, a Democrat, said on "Meet the Press" that Romney needs a bump in the polls to keep alive his presidential hopes.
Ryan, during the Fox interview, criticized Obama on foreign policy, especially the administration's efforts to prevent Iran from developing a nuclear weapon. Obama projects "weakness and equivocation in dealing with Iranian leaders, Ryan said.
''The Ayatollahs, by virtue of their conduct, don't believe the president when he says his interest is to stop Iran'' from obtaining nuclear-weapons capacity, Ryan said.
Obama in a speech to the United Nations General Assembly on Sept. 25 said the U.S. ''will do what we must to prevent Iran from obtaining a nuclear weapon,'' and that the time for a diplomatic resolution to the issue ''is not limited.''
Christie: 'A tough couple of weeks' for Mitt
Washington • New Jersey Gov. Chris Christie says it's been a "tough couple of weeks" for Mitt Romney in his presidential campaign and there's no way to "sugarcoat" that.
But Christie says there's good news on the horizon for fellow Republicans. He says Romney is going to do "extraordinarily well" in the first debate with President Barack Obama on Wednesday night. After that face-to-face meeting, Christie says "this whole race is going to be turned upside down."
Christie tells CBS' "Face the Nation" that every time Romney was backed into a corner during the GOP nomination fight, he "came out with a great debate performance because that's where he shines."