Arlen Specter Bails

Specter decides to jump, as the North effectively shakes off the Republican Party from its birthplace. There are now almost no Republican Congressmen or Senators left in New England, and mighty few anywhere north of the Ohio River.

It really comes down to electability -- specifically electability as a Republican. Specter's own statement acknowledged that his support for the stimulus bill has made his position untenable with the GOP:

It has become clear to me that the stimulus vote caused a schism which makes our differences irreconcilable. On this state of the record, I am unwilling to have my twenty-nine year Senate record judged by the Pennsylvania Republican primary electorate. I have not represented the Republican Party. I have represented the people of Pennsylvania.

Probably the most important point is here is the demographic changes going on in Specter's home state. Pennsylvania is a closed-primary state, and the ranks of registered Republicans, the folks eligible to vote in the GOP primary, shrunk last year. In 2008, between 150,000 and 200,000 registered GOPers switched to the Democratic Party in order to vote in the contentious primary between Hillary Clinton and Barack Obama.

Let's take a look at the deeper numbers -- and how the state's reduced GOP electorate has pulled harder to the right, making this move necessary as a simple matter of political survival.

Those people tended to be moderate voters -- Specter's people -- and without them he cannot win a primary. But with them staying as Democrats, he could actually start with a leg-up as a Democrat, just in case any liberal challenger might try to take him on in the Dem primary.

And the other side of this coin is that the folks who remain as registered Republicans are now proportionally much more conservative than the state GOP was before.

Remember that Specter only won his 2004 primary against conservative challenger Toomey by a 51%-49% margin -- and that was with the full backing of the Bush White House. So if we just made that demographic adjustment, Pat Toomey would have probably won the 2004 primary with all other issues being the same. And the stimulus is the final nail. The stimulus vote, and the lack of a powerful Republican establishment these days, made a defeat in the primary seemingly inevitable.

...And finally, it's important to remember another aspect of Pennsylvania politics: If he had run in the Republican primary and lost, he would not have been able to pull a Joe Lieberman and run as an independent. They have a "Sore-Loser Law" that forbids that very maneuver. So his choices other than retirement were to run as a Republican and probably lose the primary, run as an independent and face some serious structural disadvantages, or to take a chance on going over to the Democrats. And given those sets of probabilities, switching to the Dems became the obvious choice.