But Perry neither owned the stage nor dominated it. Romney and others did not hesitate to challenge the Texas governor on an array of issues, Romney striking first by citing Perry's description of Social Security as a "Ponzi scheme" and his suggestion that the popular retirement program is a violation of the Constitution and an affront to states' rights. Their spirited exchange, in a battleground state where seniors are a key voting bloc, was telling.

Social Security has been a solid program for "70 years" and said the term "Ponzi scheme" is "over the top and unnecessary and hurtful to many people," Romney said, and Perry's view that Social Security could or should be given back to the states was not only wrong-headed but politically injurious to the Republican Party. In a provocative challenge, Romney added: "The real question is does Gov. Perry continue to believe that Social Security should not be a federal program, that's it's unconstitutional and it should be returned to the states or is he going retreat from that view?"

Perry was undaunted. "If what you're trying to say is that back in the '30s and '40s that the federal government made all the right decisions, I disagree with you," the Texan said to applause. "It's time for us to get back to the Constitution. And a program that's been there 70 or 80 years, obviously we're not going to take that program away. But for people to stand up and support what they did in the 30s or what they are dong in the 2010s is not appropriate for America."

Romney pressed. "Do you still believe Social Security should be ended as a federal program as you did six months ago when your book came out and returned to the states? Or do you want to retreat from that?"

"I think we should have a conversation," Perry responded.

"We're having that right now, governor," retorted Romney. "We're running for president."

The governor of the state that includes the Alamo wasn't surrendering. "The issue is, are there ways to move the states into Social Security for state employees or for retirees? We did it in the state of Texas back in the 1980s. I think those kinds of thoughtful conversations with America, rather than trying to scare seniors like you're doing, it's time to have a legitimate conversation in this country about how to fix that program."

Romney wouldn't let it go.

"Governor, the term Ponzi scheme is what scared seniors," Romney said. "Suggesting that Social Security should no longer be a federal program....is likewise frightening. That's your view. I happen to have a different one. I think that Social Security is an essential program and that we should change the way we are funding it."

Perry had dug up his own telling quote from a Romney book. "You called it criminal. You said if people did it in the private sector it would be called criminal. That's in your book." Romney may have pinned Perry's ears back and highlighted a general election issue some Republicans fear could haunt Perry, but the Texas governor's ready-fire retort won the tea party crowd and deprived Romney of an early debate equalizer.