Sen. Arlen Specter's decision to become a Democrat was supposed to be the easy path to reelection. So much for that. Specter's move ignited a firestorm in Pennsylvania and beyond. It's left him with new enemies in both parties
...
While Sestak and others weigh primary candidacies, former governor Tom Ridge, R-Pa., is being courted by state and national Republicans to carry the GOP banner. Already, former Rep. Pat Toomey, R-Pa., -- who almost beat Specter in the 2004 Republican primary -- is in the race, and raising money at an impressive clip.
Sestak said he will be closely monitoring Specter's statements and votes over the coming months, to make sure he's helping the country move forward on areas including healthcare expansions and national defense.
"Arlen has a lot of questions to answer. If they aren't answered appropriately, I do believe we should have someone else carrying the banner for the Democratic Party, and for all Pennsylvanians," he said.
...
Sestak or another primary challenger can expect the help of liberal activists, many of whom have been waiting years or decades to defeat Specter. In addition, rifts are appearing inside the Democratic Party that could cost Specter the support of organized labor, despite the Democratic establishment's promise to rally behind its newest member. Top officials of the two largest national unions told ABC News Monday that they are unlikely to support Specter as long as he opposes their top legislative priority, the pro-unionizing bill called the Employee Free Choice Act.
Four pages of analysis here:
http://abcnews.go.com/Politics/Story?id=7509868&page=1