But the political landscape for Specter is much different this time around compared with 2004. The competitive Democratic primary between Hillary Rodham Clinton and Barack Obama last year spurred tens of thousands of Pennsylvania Republicans to switch their registration to Democratic. Specter is openly encouraging them to switch back, even telling a group of retailers he met with Monday in Philadelphia, “I don’t know if there are any Democrats in this room. If there are, I’m going to need you to become Republicans, Republicans at least for a day.”