8 p.m. ET on CNN. There’ll be other attacks on Perry tonight, whether for his allegedly “atrocious” immigration record or for the perks he’s enjoyed as governor as part of the “crony capitalism” meme, but entitlements are the jugular. Remind me again, then: Why are we obsessing over Social Security when it’s universally understood among politicos that Medicare is a much bigger/more immediate problem? Perry’s suggested that the states should have greater control over that program too, so there’s nothing stopping Romney from throwing roundhouses at him for allegedly wanting to pull the plug on grandma or whatever. Any theories? Any explanation for why Mitt Romney might not want to turn the debate towards a discussion of state-provided health care?

Marc Thiessen spies an opening for Perry if he’s willing to exploit it:

In his address to Congress last week, Obama proposed a 50 percent cut in the payroll taxes that fund Social Security. Obama’s plan would extend and deepen the one-year cut he signed into law last year, reducing both employee and employer contributions from 6.2 to 3.1 percent through 2012. This would rob the Social Security trust fund of about $175 billion in financing next year (money Obama would replace with new debt). Obama’s proposal is generating opposition from conservatives on Capitol Hill. Rep. Pete Sessions (R-Tex.) says “it is a horrible idea” to cut the amount of money Americans pay into Social Security at a time when the program is at risk of insolvency.

This creates an opportunity for Perry to go after Obama for gutting the Social Security trust fund — pointing out that last year, for the first time in three decades, Social Security spent more on benefits than it collected in payroll taxes, and that Obama’s actions are making the program even more financially unsound.

But Obama is not the only politician who announced last week that he wants to dip into Social Security’s coffers. In his newly released economic blueprint, Mitt Romney endorsed . . . a payroll tax cut. It would be fair for Perry to ask how Romney can claim that that he wants to “save” Social Security when his own economic plan would raid the Social Security trust fund?

Yeah, I don’t know. Perry needs to polish his messaging on this but “more money for Social Security” may be, shall we say, a bit too polished. Over at the Corner, Mark Steyn and Rich Lowry are hammering Romney for pursuing a strategy on this issue that plays directly into the image of him as a cynical, calculating flip-flopper who’ll say what he needs to say to get elected. I’ve made that point before myself, but let me play devil’s advocate: Is there anything Romney could say or do at this point to erase that image? It’s priced into his stock. He’s making a bet, not unreasonably, that in the end most Republican primary voters care chiefly about unseating Obama, not who does the unseating. If Mitt can convince them that Perry would be a risk in the general, they’ll tilt towards him, cynicism and all. This is the byproduct of the base believing that Obama’s the worst president ever: In theory, the truer that is, the more important electability will be in the nominee.

While we wait, here’s a snippet of Rush Limbaugh’s long monologue today warning Romney and Bachmann not to demagogue the “Ponzi scheme” point lest their own past rhetoric to that effect be used against them. True enough: Bachmann called Social Security a “tremendous fraud” just last year and Romney’s new best friend, Tim Pawlenty, explicitly described it as a “Ponzi scheme” — twice! — on CNBC in December 2009. Rush claims, though, that Romney’s describing the program in these terms in order to ingratiate himself with the media. Is that right? Remember this data point from April of last year:

“TP” stands for tea partiers, of course. Even Republican voters love their entitlements, enough so at least to want to keep them around so that they can get a return on their FICA investment/Ponzi contribution. Here’s the clip; below that, as always, you’ll find the handy dandy Hot Air/Townhall Twitter widget for live updates during the debate. Happy watching.