Specter's relentless barrage of negative ads is aimed at preventing challenger Joe Sestak from making inroads with the 25 to 30% of Democratic voters who remain undecided.
Specter is hitting Sestak with everything from his congressional attendance record to sub-minimum wage pay for some campaign workers.
However, the big bomb continues to be Specter's all-out assault on the former admiral's military record.
An announcer in a Specter campaign ad against Sestak says "Joe Sestak: relieved of duty in the Navy for creating a poor command climate."
Sestak has been forced to counter the attacks with TV ad money he'd rather be using to introduce himself to voters.
"Please, Mr. Specter, don't lie about Mr. Sestak's distinguished service record," a man says in a Sestak campaign ad.
Specter's been hyping Sestak's 2005 dismissal from a top Pentagon job in a dispute over fleet size as something akin to mutiny.
"Voters are entitled to know why he was relieved of his command. I think it goes to character, it goes to competency," Sen. Specter said.
"My commanding officer said it well. He said I stood up to people who didn't want to be challenged, I was a patriot's patriot, I was courageous," said Rep. Sestak.
Despite his double digit leads in most polls, Specter has been forced to take a calculated risk with the attacks on Sestak's service record."
"The only way Joe Sestak can win the Democratic primary is to win the lion's share of those undecideds. Specter is, in a sense, taking a calculated gamble, and the gamble is there won't be blowback from the commercials," said Terry Madonna of Franklin and Marshall University.
"Negative campaigning works even when the public decries it and says they don't like it. We know, in fact, the public does like it," said Prof. Randall Miller of St. Joseph's University.
Sestak has enough money to remain competitive with Specter in Pennsylvania's five major media markets.
