It’s complicated.

Pennsylvania is a “purple” state that must go Democrat blue instead of Republican red for Barack Obama to win the November election. John McCain does not need Pennsylvania to win the White House, but Obama sure does.

Matt Lebo, a political science professor at the State University of New York’s Stony Brook campus, says that even with new states in play for Democrats, a winning electoral map for Obama without the Keystone State is difficult to envision. “If Obama were to lose Pennsylvania, it would be because he didn't appeal enough to her voters, even less so than John Kerry” in 2004, he says.

Lebo reasons that losing Pennsylvania in the fall points to larger problems. “Whatever it would be that would hurt him to the point of losing there, would also hurt Obama elsewhere, especially in Michigan and Ohio.”

University of Virginia professor Larry Sabato explains that America’s political landscape is like playing with 50 pieces of a complicated puzzle: “There are thousands of potential combinations of electoral votes, with over 80 ways the Electoral College can tie, and about 30 reasonable combinations that produce a tie.”

Sabato says that if Obama is losing Pennsylvania going into November, it will be a bad sign for his candidacy. “That would suggest that other, even more competitive states may be going to the Republicans.”

Pennsylvania has grown comfortable in her role as a battleground state. A high-roller in both the 2000 and 2004 general elections, the Keystone State became the center of the political universe this spring with the unprecedented six-week primary race between Obama and Hillary Clinton.

Clinton won on sheer political tenacity and a lot of sideline heavy-lifting by Gov. Ed Rendell’s political machine. Of the state’s 67 counties, Obama won just seven.

“One of the main reasons that Barack Obama did not do well here in the primary is that he is a ‘change’ candidate and we just don’t embrace change,” says Philadelphia Democratic analyst Larry Ceisler.

Ceisler, a Western Pennsylvania native, says most Pennsylvanians are born and die in the state and, “even if we lose our jobs, we stay here.”

He says Obama faces some obstacles among state machine politicians. For example, “he did not play the street-money game in Philadelphia and there is resentment for that. … He probably did not get a good black vote because of that.”

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.