After boosting his favorables over the last few weeks and getting to within single digits of Arlen Specter in the Pennsylvania Senate primary, Joe Sestak pivoted today – and hammered Specter for his ties to national Republicans for 30 years.

The quote of Specter saying “My change in party will enable me to be re-elected” is pretty devastating, and Sestak builds around that the familiar images of Specter hobnobbing with George Bush, Rick Santorum and Sarah Palin. It closes with the line, “Arlen Specter switched parties to save one job. His. Not yours.”

In a statement, Sestak campaign manager Jonathan Dworkin said, “This election is about who we can count on to represent our values on the day after the election and for the next six years. Many Democrats are skeptical of why Arlen Specter switched parties after enthusiastically touting the endorsement of President Bush. But there is no way Senator Specter can make his motives more clear than he does in his own words.”

We’ve seen this election cycle that advertisements haven’t totally led to a rise or fall in fortunes. But in Pennsylvania, Sestak’s ad blitz has brought him close. We’ll see where this hit on Specter leads. Frankly, I’m surprised it’s taken this long for him to play this card.