As an old high school friend pointed out, this news of Specter switching Parties is that much more ominous when you look at this post from Arlen's twitter feed back on April 21st.
So now we can safely assume it will be Specter vs. Toomey in the general election next year. Some have said that this dooms Toomey's chances since Pennsylvania isn't prone to electing hard right conservatives.
Well to those I say, don't forget Sen. Rick Santorum - a social conservative who represented PA up until 2006. Santorum lost for a couple reasons, increased negative environment for Republicans at a national level and an opponent in Bob Casey who was widely known and opposed to abortion, thereby stealing one of Santorum's biggest constituencies.
So what does this mean for Specter v. Toomey?
Well now you have a pro-choice Democrat who betrayed his old base and of late, has been popular with Democrats and split with Independents.
The question becomes, how will Independents react to the switch? Will they see it as the obvious political, rather than idealistic, move that it is? If so, will that turn them off or have they become so cynical that they don't care?
I think it's safe to assume that Republicans will have the edge in GOTV. They'll be ticked and want their revenge against the one that betrayed them. Without Obama on the ticket, this will make it more difficult to inspire Democrats to go out and vote for the guy without any scruples.
But at the end of the day, this race will come down to what most toss-ups in 2010 will be about - the economy.