President Obama heads into his reelection campaign with a precarious standing in the must-win state of Pennsylvania, a new poll shows.

Fifty-two percent of the state’s voters disapprove of the job Obama is doing, while 42 percent approve, according to the survey by Public Policy Polling, a Democratic-leaning firm based in Raleigh, N.C.

Interestingly, the poll finds Obama in a statistical dead heat with three potential Republican opponents among Pennsylvania voters. Most recent surveys have shown Obama lagging against a generic “Republican candidate” in 2012, but more comfortably ahead of actual named GOP opponents in ballot tests.

Obama trails Mitt Romney 42 percent to 43 percent, leads Mike Huckabee 45 percent to 44 percent, and leads Rick Santorum 45 percent to 43 percent in Pennsylvania, the poll finds. All of those spreads are within the poll’s 4-percentage-point margin of error.

In 2008, Obama cruised past Republican John McCain in Pennsylvania by 10 percentage points.

The poll shows that Obama’s problem in the state is coming from independent voters and white Democrats. A majority of independents disapprove of the president’s job performance – 54 percent give him bad marks to 39 percent who think he's doing a good job. More significantly, Pennsylvania Democrats give Obama an overall approval rating of 68 percent, well below the national average PPP has found of 81 percent.

Black Democrats give Obama an 86 percent approval rating, down slightly but still strong. White Democrats, however give him a 64 percent approval rating, versus 27 percent who disapprove.

“Obama’s big problem in Pennsylvania right now is keeping conservative white Democrats in line,” said Dean Debnam, President of Public Policy Polling. “They voted for him in November 2008 after supporting Hillary Clinton in the primary, but they have not liked what they’ve seen in his first two plus years in office.”

PPP surveyed 593 Pennsylvania voters between April 7 and April 10, using a touch-tone computer response system. Results are subject to a statistical error margin of plus or minus 4 percentage points, the pollsters say.