From Real Clear Politics:
The possibility that Specter's primary switch could lead him to still lose his primary has to be giving conservatives a serious case of schadenfreude. No polling yet on the Specter-Sestak matchup, but I'd expect some in the next few days. On the other hand, this probably pushes Specter to the left for the remainder of the term, which means that more of Obama's agenda becomes a reality.
Sestak's district is a swing district (D+3), so it opens up an opportunity for the Republicans, especially if recruiting is stronPost Optionsg and things begin to go south for the Democrats.