As you have probably heard by now, Arlen Specter, the longtime Pennsylvania Republican has switched to the Democratic Party. He states that the switch is due to the shift of the Republican party to be more conservative. This is entirely true, and probably the ultimate reason of him switching.
Once Al Franken is seated this will give Democrats the filibuster-proof majority in the Senate. He is not doing this to give the Democrats the advantage though. He is doing this for political survival.
Due to his very moderate stances, Specter was a prime target for a Republican challenge in the 2010 primaries. In fact, he would likely have lost lost that primary to a more conservative challenger. He would have been safe after making it past the primaries, but you have to make it to the general election to have a chance.
New polling shows that Arlen has a much better chance as a Democrat. This move will probably save his political career. I’m sure that if he wouldn’t face a major competitor in the primaries he would have remained in the Republican column. The Republicans did it to themselves.
That polling shows a 71% approval/16% disapproval rating from Democrats, compared to 36% approval/52% disapproval from Republicans. That is an insane approval rating for the opposite (now same) party. After this switch I wouldn’t be surprised if the approval rating lowers for the Democrats. When he was from the other party Democrats liked his moderateness and his willing to cross the aisle. I think Democrats will be more disappointed when he sides with the Republicans. Though, I think he will retain a positive approval rating. His approval rating from Republicans may even go up in the long run (but probably down in the short).