I can't speak for what's going on in Philly, sadly you are right they do determine statewide elections... and the Dems have a huge target on Santorum.. no doubt.
The question though, is in an off year election, will these folks show up at the polls on election day? Questionable.
We'll see where we are in September. Immigration issue is going to have bigger play in Philly than anywhere in the state IMHO... and Casey is on the wrong side of that one
Turned out to be an interesting day for Senator Santorum.
Hopefully he'll see a boost in the polls because of this. If the race tightens, perhaps Junior will crack under the pressure.