Poll shows Romney leading Santorum in Pennsylvania

— -- HARRISBURG, Penn. -- Three weeks before the Pennsylvania Republican primary, a state poll shows Mitt Romney leading Rick Santorum by five percentage points.

Santorum, who trails Romney by hundreds of delegates, has acknowledged that Pennsylvania is a must-win for his campaign. Santorum represented the state in Congress from 1991-2007.

Here's the breakdown from the Public Policy Polling survey:

Last month, Romney polled at just 25 percent to Santorum's 43 percent in Pennsylvania, a positive swing of 17 percentage points for Romney.

"The momentum in Pennsylvania is moving completely against Rick Santorum," said Dean Debnam, president of Public Policy Polling, a Democratic firm.

The survey of 402 likely Republican voters in Pennsylvania has a margin of error of plus or minus 4.9 percentage points.

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