Dick Polman looks at the demographics:
After Mississippi votes next Tuesday, Pennsylvania will become the new Iowa, the target of unremitting national attention, and it will be a brutal battlefield. For all the glib comparisons to Ohio, its Rustbelt neighbor, there are significant differents that could aid Obama. It has a larger black population than Ohio, and a larger student population. In contrast to Texas, it has a small Latino population. It has populous white liberal suburbs around Philadelphia.
On the other hand (advantage Hillary), it has the second-largest senior electorate in America, behind Florida. It has a large population of lunch-bucket guys, just as in Ohio. And, perhaps most importantly, this primary is open only to registered Democrats. Obama-friendly independents need not bother to show up - unless they re-register as Democrats in advance, by the March 24 deadline.
You have till March 24.