Obama leads with 49 percent support in Pennsylvania against Romney's 40 percent. That’s in line with the Real Clear Politics average of polls, which shows Obama ahead by 7.7 percentage points.

While Obama’s job approval rating is underwater in the poll, 43 percent approve versus 47 percent who disapprove. Romney’s favorability rating is even worse, at 37 positive and 49 negative.

Pennsylvania is one of 12 key swing states that Obama won in 2008 that will be critical in determining the outcome of the 2012 election. Pennsylvania’s 20 electoral votes are the third-most at stake among swing states, behind only Florida and Ohio. 

Obama won Pennsylvania by 11 percent over Sen. John McCainJohn McCainOvernight Defense: General warns State Department cuts would hurt military | Bergdahl lawyers appeal Trump motion | Senators demand action after nude photo scandal Senate lawmakers eye hearing next week for Air Force secretary: report House Intel chairman under fire from all sides MORE (R-Ariz.) in 2008.

The poll of 422 likely voters was conducted between Aug. 16 and Aug. 20 and has a five percent margin of error.