Once a high-profile presidential candidate is on record calling Social Security, one of the nation’s most popular and successful programs, a “Ponzi scheme,” it’s tough to walk it back.

Indeed, while Republican hostility for Social Security isn’t exactly new, Republican presidential hopeful Rick Perry has taken this to an unfamiliar level. He’s not only dismissed the bedrock program as a “Ponzi scheme,” the Texas governor has also said Social Security is unconstitutional, and could be turned over to the states (it can’t).

Perry is at least sharp enough to know these criticisms can cause him some trouble, but if a campaign stop in New Hampshire yesterday was any indication, the governor isn’t quite sure how to deal with Social Security scrutiny.

Inside the cafe, Gail Mitchell and a companion grilled him: “You said Social Security was unconstitutional.”

“Social Security’s going to be there for those folks,” Perry answered his inquisitors, making reference to the elderly.

“But you said Social Security is unconstitutional,” Mitchell repeated.

“I don’t think I — I’m sorry, you must have,” Perry said before stopping himself.

Instead of elaborating, Perry stuffed a generous piece of popover in his mouth. (Perry called them “pop ups.”)

“I’ve got a big mouthful,” Perry said and then ordering a glass of water. He later tripped over one of the women standing at his side pressing him on Social Security.

“I’m sorry, sweetheart,” Perry said to her.

When a candidate would rather stuff food in his mouth than answer an important question, it’s safe to say he considers the issue politically problematic.

Later, Ray Sullivan a Perry campaign spokesperson, told reporters he’s “never heard” the governor question the constitutionality of Social Security.

Sullivan may be the only one.

As for Perry’s reluctance to stand by his own positions, what happened to the swagger, Rick? Folks want to know if you stand by what you said about Social Security. You’re not going to let polls and a bunch of aides tell you what to think, are you?

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.