WASHINGTON —  A Philadelphia real estate broker who was Sen. Rick Santorum's only Republican primary challenger is dropping out of the race.

John Featherman said Wednesday that he decided it wasn't worth the money to fight the state Republican Party, which on Tuesday challenged his application to be on the ballot.

Featherman filed 2,207 signatures with the application. The Secretary of State's office tossed out 185, and the party filed a challenge to 1,073 signatures, said Scott Migli, executive director of the state GOP. The party cited errors such as blank boxes and Democrats who signed the petitions.

"I didn't see the sense in making our side spend any more money," Featherman said.

Featherman got just under 48,000 votes in a race against Santorum, Democrat Ron Klink and two other candidates as the Libertarian Party's nominee in 2000. He also ran unsuccessfully for Congress in a special election in 1998.

Democrat Bob Casey has led Santorum in the polls.