Obama leads with 51 percent support to Romney's 44. That’s down from Obama’s 52 percent to 40 percent lead in the same poll from mid-September. Obama still leads by 4.5 percentage points in the Keystone State, according to the Real Clear Politics average of polls.

Obama is buoyed in Pennsylvania by independent voters, who favor the president 51 percent to 41 over Romney. In addition, male voters, who typically lean toward Romney, go for Obama 48 percent to 46 percent in Pennsylvania, according to the poll.

A win by Romney in Pennsylvania would dramatically alter the race and greatly increase his chances of winning.

No Republican presidential candidate has won Pennsylvania since President George H.W. Bush in 1988.