Pat Toomey has taken to the airwaves in limited markets (read: not Philadelphia) with a new spot almost certain the devastate Sestak’s candidacy. The spot features Sestak telling a reporter, “I want to be this president’s strongest ally.”

But President Obama is seen favorably by only about 40 percent of Pennsylvanians. And an overwhelming percentage don’t like what they’ve seen over the past two years. Pessimism reigns in the Keystone State.

The ad undercuts the central theme that Joe Sestak has worked to cultivate with endorsements from outsiders like Michael Bloomberg, Chuck Hagel, and Bill Clinton — that he’s not radical, that he’s independent, that he’s non-ideological.

Cue David Gregory’s incisive tee-off: “You voted for TARP, for the bailout, you voted for the president’s stimulus plan, you voted for the president’s healthcare plan. Exactly which establishment are you not part of that you’re running against?”

Sestak, “strongest ally” of an ill-favored president and 97-percent supporter of Nancy Pelosi, may have helped sow the seeds of his own electoral defeat with this proclamation in the same way vanquished Arlen Specter did when he crowed that his change in party would allow him to be “re-eleeecteeeeed.”

It’s a knock-out.