Back in 2011, Pennsylvania state legislators toyed with the idea of changing their electoral college vote system so that they would align with already-gerrymandered Congressional districts. Ultimately they didn't go with that idea, but that doesn't mean it died.
Shortly after the November election, that idea was floated again. Stung by the "shocking" outcome of the 2012 general election, Senate Majority Leader Domenic Pileggi proposed changing the electoral college votes from winner-take-all to apportionment by Congressional districts.
But it isn't just Pennsylvania. It's Michigan, Ohio, Florida, and Virginia, too. Via fairvote.org:
A little number-crunching demonstrates why. If Republicans in 2011 had abused their monopoly control of state government in several key swing states and passed new laws for allocating electoral votes, the exact same votes cast in the exact same way in the 2012 election would have converted Barack Obama's advantage of nearly five million popular votes and 126 electoral votes into a resounding Electoral College defeat.
The power of elector-allocation rule changes goes further. Taken to an extreme, these Republican-run states have the ability to lock Democrats out of a chance of victory in 2016 absent the Democratic nominee winning a national landslide of some 12 million votes. In short, the Republicans could win the 2016 election in by state law changes made in 2013.