The five-term Pennsylvania Republican has started losing his hair from chemotherapy treatments, which he described to reporters as "tough but tolerable." But he reiterated that he's keeping a full schedule and looking ahead to his next election.
Specter, 78, said it "worries me a lot" that leading up to the state's April 22 Democratic primary between Sens. Hillary Rodham Clinton and Barack Obama, Republican registrations in the state dropped nearly 2 percent from the fall.
Meanwhile, Democrats had more than 4 million voters registered for the primary, a nearly 8 percent increase from the November election.
Specter said he thinks many of the voters switched their registration just so they could vote in the Democratic primary and will switch back. But it is "going to take some work" to get some of them back, he said.
In 2004, the moderate Specter nearly lost the GOP primary to former Rep. Pat Toomey. He said he anticipates he'll face a tough primary again and wants independent-minded voters to be registered in the Republican Party so they can vote for him.
To help bolster GOP registrations, Specter said he's talking to his major contributors about donating money as part of the effort to increase party registration.
He said he's asked presumptive Republican presidential nominee John McCain to help out with the effort to increase Republican registration in Pennsylvania, which is likely be a competitive state in the presidential election. He said McCain will be in the state June 30.
Also, he said he's helping Senate Republican Leader Mitch McConnell of Kentucky with a fundraiser in Philadelphia next week.
Associated with that, he said he's organized a press conference with GOP House challengers to help them get out their message.
In April, Specter was diagnosed with a recurrence of Hodgkin's disease, which is a cancer of the lymphatic system. He also underwent treatments in 2005 and had been given a clean bill of health.
