The Illinois senator is trying to get independents and Republicans to flip their official party registration so they can vote in the Keystone State's April 22 closed primary, Politico reported.

The voter registration deadline is March 24. Obama is competing with Sen. Hillary Clinton for the Democratic presidential nomination. The New York senator leads in polls in Pennsylvania.

"The more we can get, the better our chances to overcoming these advantages the Clinton campaign has," said Obama spokesman Sean Smith.

The number of party-change applications in February jumped 250 percent from a year earlier, compared to a 65 percent increase in January, Politico reported, citing state Department of State figures.

Jeremy Bird, Obama's Pennsylvania field director, appealed for volunteers this week, Politico said.

"Here in Pennsylvania, hundreds of thousands of unregistered voters are ready to support Barack," Bird said.

"But we have only two weeks to reach out to them all. That's why people from all over the country are traveling to Pennsylvania to make sure every potential Obama supporter is registered and eligible to vote in the primary on April 22," he added.