Texas Gov. Rick Perry, it seems, is trying to do two inherently contradictory things. On one hand, he is trying to avoid walking back his previous comments and writing on Social Security; on the other, he seems aware that those views are not sustainable, even in a primary.

In an interview with Time, he put aside his previously incendiary rhetoric and tried to move his position toward the mainstream. He is keeping his indictment of the system. (“There may be someone who is an established Republican who circulates in the cocktail circuit that would find some of my rhetoric to be inflammatory or what have you, but I’m really talking to the American citizen out there. I think American citizens are just tired of this political correctness and politicians who are tiptoeing around important issues. They want a decisive leader. I’m comfortable that the rhetoric I have used was both descriptive and spot on. Calling Social Security a Ponzi scheme has been used for years. I don’t think people should be surprised that terminology would be used.”) However, he’s not repeating the argument that it is a “failure” and didn’t bring up devolving the program to the states. He doesn’t actually say (or likely know) what he’s going to propose but it sounds like a dozen other ideas that have been in circulation:

We need to make sure that those on Social Security today — and those approaching it — know without a doubt it will be in place. It will not go away. We’ll have a transitional period for those in mid-career as they’re planning for their retirement. And our young people should be given some options. I don’t know what all of those options need to be yet, but they know instinctively that the program that is there today is not going to be there for them unless there are changes made.

Meanwhile, Mitt Romney isn’t letting go. Understandably, he’s got Perry on the run on this one, and now has an opportunity to make the case that he’s got his finger in the wind on an important issue. In Arizona yesterday, he hammered the issue home again. The Romney campaign was quite happy to send around this report from the Arizona Republic:

Romney, a former Massachusetts governor, has emerged in the GOP field as a defender of the popular but financially stressed safety-net program for older Americans. During a televised debate Monday, he took Texas Gov. Rick Perry, his chief GOP rival, to task for calling it a Ponzi scheme. He continued to hammer his support for the program before a mostly friendly audience of about 500 people in a packed ballroom at Oakwood Country Club.

“I will save Social Security financially and as a federal program and a federal entitlement,” Romney said during a 60-minute, town-hall-style meeting.

Notice the emphasis on “federal” and the implicit rejection of the dopey idea of sending Social Security back to the states. He’s going to keep this up, I suspect, until Perry repudiates his views on a state retirement system:

Romney took several shots at Perry, some veiled and some direct, over Social Security. Romney characterized Social Security as a savings plan or pension plan that has worked for 75 years while stressing that it is not a Ponzi scheme. He acknowledged that Social Security “absolutely” faces financial trouble in the future and that reforms are needed in order to keep the program solvent for younger Americans who are now working.

“There’s no change needed for people who are currently retired or near retirement,” Romney told the almost exclusively senior crowd. “But for those that are in their 20s, 30s and 40s, we’re going to need to change the system somehow. . . . But don’t worry, it’s not going to change for anybody in this room.”

My colleague Greg Sargent is trying to figure out whether Perry’s tactic is an intentional courting of the base or whether Perry suffers from a lack of verbal discipline. My own take is that Perry has decided that the ”Ponzi scheme” is the least of his problems, especially in the primary. He can continue to use that sort of rhetoric because it allows him to claim political courage in speaking hard truths to the public (but where is his plan?) and to convey toughness in adhering to his previous views. This is a pol who is highly competitive and plainly loathes the idea of apologizing or retracting his positions. (Just look how long it took him to renounce an opt-out mandatory HPV vaccination plan.)

This approach works so long as two things don’t occur. First, he can keep this pretense of bravery up until someone else in the race comes up with a concrete plan. And second, he can keep the balls in the air so long as a feisty interviewer, debate moderator or opponent doesn’t really press him on whether the system is a failure or whether it makes sense, as he advocated in his book, to send it to the states. You can understand why he hasn’t gone on Meet the Press or met with a national newspaper’s editorial board.

The problem for Perry is not confined to Social Security or to HPV vaccinations. He’s said and written controversial stuff about letting states legalize pot. He’s called for the repeal of the 16th and 17th Amendments. He wrote and said for a very long time that gay marriage should be a state issue. The tension between Perry the Tea Party leader and Perry the presidential candidate continues. Rather than set out bold policies and speak in moderate tones, he’s avoided specific policy proposals and tried as best he can to defend his rhetorical excess. That is hard to keep up in a long and tightly contested presidential campaign. And it’s even harder to do in a general election against an incumbent president with nearly unlimited resources and a determination to run the most negative campaign possible.

All of this would be greatly aided if Perry could go beyond platitudes. He wants a “discussion” on Social Security. He wants to cut spending and keep taxes low. Swell. But really, does he have ideas and is he willing to go to bat for them even if they wind up unpopular with his own party (e.g. spending more on national defense)?

It’s ironic that his campaign so closely resembles Obama’s 2008 run, in which the Democrat tried to keep the slate as blank as possible. Hey, it worked in 2008 so might it work again? Well, the problem is that Perry has to run against an opponent who never spelled out in detail what he wanted to do, wasn’t properly vetted and turned out to be a huge disappointment to many who voted for him. Does Perry really want to try that gambit? More importantly, can his opponents convince the electorate that this sort of candidate is too risky?