Despite Ed Rendell’s best efforts to push Joe Sestak out of the race, Sestak isn’t backing down. Sestak was on ABC’s TopLine with Rick Klein trying to position himself:

It would be disappointing [if] the Washington political establishment of my party — which, and I respect those individuals in it. . . dictated who would be anointed to be the primary candidate.

Rendell said that Sestak would get "killed" in a primary. However, a new Susquehanna Research poll indicates that 63% of Pennsylvanians think Specter should face a Democratic primary challenger.

Sestak had $3.3 million in the bank as of the end of March. He could certainly afford to run a primary race, and if Specter’s numbers are as soft as they appear to be, Rendell knows very well that Specter could be beaten.

But Sestak voted for retroactive immunity for the telecoms last year, and, unlike Specter, he has yet to sign on to the State Secrets Act to limit the President’s ability to force the dismissal of lawsuits by claiming secrecy. In his TopLine interview Sestak also reiterates his opposition to gay marriage. His ability to rally serious support from those who traditionally favor challenging the party establishment remains to be seen.

The elephant in the middle of the room is still the unions. There are 900,000 union members in Pennsylvania, and to give you an idea of what that means in Pennsylvania, Bob Casey got 2.36 million votes to Santorum’s 1.66 million in the 2006 general election. If Employee Free Choice comes to a vote and Specter is the 60th vote for cloture, the unions will no doubt support him.

But if Blanche Lincoln and others continue to oppose EFCA and it never gets to the floor, there is no love lost between Specter, and the unions and they have no reason to back him over Sestak. Ironically, the opposition of Lincoln, Webb and others to Employee Free Choice could well be the thing that costs Specter the nomination.

President Obama enjoys a 91% approval rating among Pennsylvania Democrats, and he has pledged to campaign for Specter. How far he’s willing to extend himself on Specter’s behalf will no doubt be a function of how well Specter supports his agenda. With Sestak still considering a primary challenge, Specter’s willingness to support the President is probably growing stronger every day.