Spectre will not survive the PA primary, he got by the last time by the skin of his teeth due to endorcements by Bush and the small majority held by R’s. This time R’s are in the minority, those that held their nose and voted for him last time won’t do it this time.
The support of the porkulus assures that Spectre will lose the republican primaries. Now, again, that doesn’t mean he won’t run as an independent and possibly win the state in the general, but I see no calculus in which Spectre wins the R. primaries.
2010 will be a completely different race. The last time Specter ran, the GOP was worried about losing a seat and the majority in the Senate, so Santorum and the GOP went all out out back him, since they believed he would be the best candidate to beat the Democrat. Protecting a majority is no longer an issue, so there’s no reason to back Specter over Toomey.