U.S. Sen. Arlen Specter on Tuesday was defeated in a Democratic primary in his bid for a sixth term after taking the risky step of switching from the GOP. Voters picked U.S. Rep. Joe Sestak as the party's nominee and rejected the 80-year-old Specter in his first Democratic campaign since his Republican Party defection. With 79 percent of precincts reporting, Sestak received 435,630 votes, or 53 percent; Specter received 384,027 votes, about 47 percent. Advertisement The vote also was a defeat for President Barack Obama, who supported Specter when he abandoned the Republican Party last year. In speaking to supporters at a downtown Philadelphia hotel after the race was called, Specter thanked Obama for his support.