Hillary Open Big Lead in Pennsylvania

The New York senator has lengthened her lead in Pennsylvania to 52 percent, over Obama's 37 percent, according to a Rasmussen Reports poll conducted last week - a near four-fold increase on the 4-percentage-point lead she had in February.

The campaign is not resting on those numbers ahead of the April 22 primary, however.

"We're going to try to really blanket the state with visits" by Clinton, the former president and their daughter, Chelsea, said Pennsylvania campaign spokesman Mark Nevins. "We anticipate we'll be very aggressive all over the state."