Ceisler says Obama's map to winning the state is the same map that any Democrat uses: “Roll up big numbers in the city of Philadelphia and just not get your head handed to you in Western Pennsylvania and the rest of the state.”

“McCain is going to be extremely competitive in Pennsylvania,” he warns. “I think from a personality standpoint, he is going to play very well.”

McCain’s potential challenges here will be the same that they are in every rust-belt battleground: his economic message, his position on the war, and George Bush as baggage.

Oddly, McCain’s age works for him in Pennsylvania; lots of older voters will be happy to support his candidacy rather than risk someone younger.

The key for McCain is to win over Clinton Democrats from the primary as well as to maximize turnout among Republicans and pro-McCain coalitions.

He needs geographical voting blocs to go his way, too. He must win the traditionally conservative “T” across the top of the state and down the center – but he also must “corner” Obama, meaning a four-corner strategy of wins in Erie (the northwest), Allegheny, Washington and Westmoreland counties (the southwest), Scranton, Lackawanna, Luzerne and Wilkes-Barre (the northeast) and Bucks County (the southeast).

If he can box Obama in those regions, he’ll win Pennsylvania and the White House.

Ceisler cautions that Democrats should not forget “the Ridge factor” – former two-term Republican governor Tom Ridge, considered a hometown boy from Erie down to Allegheny County – “even if he is not on the ticket.”

Ceisler, Lebo and Sabato all agree that while it is not impossible for Obama to win without Pennsylvania, it will come down to how many red states turn blue, and whether they are enough to compensate.