I'm sure Santorum has enough soft supporters in PA to lose it if he's only up by 4% at this point. That would really be only a fraction of what he's bled elsewhere, although maybe losing the last couple of primaries has already shaken all of the leaves from the tree.
Per Trende's demographic model, Mittens should be ahead in PA by about 5 points, and with him running about 4-5 points ahead of the model, make it 10 points. So if you give Rick at least 5 points for the home state advantage, the PPP poll having Mittens 5% ahead does not surprise me.
