The Romney campaign’s initial ad buy, which includes a pair of television spots, also won’t air in Pennsylvania (although to be fair, the spots are running in only four states – Virginia, North Carolina, Ohio and Iowa, and he has visited the state twice since locking up the GOP nomination, according to the Hotline candidate schedule tracker).

Understanding why the GOP candidate might be skeptical about Pennsylvania isn’t difficult. A Republican presidential nominee hasn’t triumphed there since George H.W. Bush in 1988, and, as mentioned, Obama won easily there four years ago despite a heavy investment of time and money from the McCain campaign. The state has more than a million more registered Democrats than Republicans, and an early May poll from Quinnipiac University found the president leading over Romney 47 percent to 39 percent. …

Romney’s skepticism toward Pennsylvania shouldn’t be taken as an indication of weakness in his campaign — he can still easily reach 270 electoral votes without winning there. In fact, if Romney did beat Obama in Pennsylvania, it’s a likely indication that he not only won the presidential election, but he did so in a landslide. But it’s an interesting representation of the electoral map’s shifting ground, swinging away from predominantly white states like Pennsylvania and toward new battlegrounds in more diverse states like Virginia and Colorado.