I think he's been testing some responses: "Don't want to end it for those currently or about to receive it...thinking about future generations of workers...blah, blah, blah." But those are weak at best and will just lead to additional questions. He's kind of painted himself into a corner on this one and a few other as well.
Voters haven't understood this in elections past. Democrats scored points building arguments on the ridiculous premise that Social Security was sustainable. Those days are over. A majority won't buy that crap anymore.
Even if I'm wrong about that, Republicans have to tell the truth about Social Security and let the chips fall where they may. If the electorate falls for the Dem-agoguery again the nation is doomed. Republicans have to plant their flag, make their stand and fight the fight we need to have. Either the Dems get a mandate for decline or the GOP gets a mandate to do what needs to be done to avoid it.
Perry has planted his flag exactly the right strategic spot. It's time to rally ‘round.