Sen. Specter has been challenged from the right before, but never by anyone so formidable. And the political demographics are working for the challenger. Pennsylvania once was described as a state with two big cities — Philadelphia and Pittsburgh and their suburbs — as bookends, with the rest of the state resembling Alabama with no African Americans. Republican primaries used to hinge heavily on the four big suburban Philadelphia counties. Now, notes Rick Robb, a longtime GOP operative in the state, “the growth of the party” is west and north of that region — Lancaster and York and Lehigh Counties.