Washington (CNN) - Democratic Rep. Joe Sestak has put out his first television ad in the Pennsylvania Senate race. The spot, which casts Sestak in a positive light, is being greeted by a harsh ad from his opponent.
Sestak is battling Sen. Arlen Specter for the Democratic nomination. The primary is May 18.
In Sestak's 60-second spot, which began airing across Pennsylvania Tuesday, the two-term congressman introduces himself to voters who may not know him statewide.
"Meet Joe Sestak," the ad begins. It goes on to highlight the congressman's 31 years in the Navy, his rise to become a three-star admiral and notes that Sestak is "not a career politician."
While not mentioning Specter by name, the ad appears to slam the senator.
"If we want real change in Washington, we can't keep sending the same career politicians to represent us," Sestak said in the ad.
In a statement to CNN, Sestak's campaign spokesman laid out what he said was "a clear choice for Pennsylvania."
"Someone who dedicated his career to advancing the GOP agenda and switched parties to try to save his own job, or someone driven by Democratic values," Sestak spokesman Jonathon Dworkin said.
Last spring, Specter switched parties from Republican to Democrat. He was first elected to the Senate in 1980.
Specter is not letting his opponent's new ad go unanswered.
In the senator's campaign commercial, also released Tuesday, an announcer says "Joe Sestak – relieved of duty in the Navy for creating a 'poor command climate.'" The ad also accused Sestak of missing 127 votes in the House, "the worst attendance of any Pennsylvania congressman."
In a separate statement sent to CNN, Dworkin fired back at Specter.
"It's disappointing that after 30 years in Washington, Arlen Specter can't run on his own accomplishments," he said. "So while Joe Sestak is running a positive TV ad about his accomplishments and his agenda for changing Washington, Specter has launched a Republican-style negative campaign in his TV ads."
According to a recent Quinnipiac University poll, Specter holds a 53 percent to 32 percent advantage over Sestak in the Democratic primary matchup, with 15 percent undecided.