Arlen Specter has come out of the closet – partially. He has gone over to the Democrats because… because…
Well, no one short of his conscience – the conscience of a moderate – knows why.
But here’s a wholesome guess: Arlen is getting along in years; the power vector has shifted from Republicans to Democrats, which means Republican congressmen can not expect in a government controlled by Democrats to wield any influence as party chairmen.
But Arlen can – if he switches parties and wins.
One expects Democrats to be appreciative and buy the guy off with a chairmanship of something or other.
Better to go out as a traitorous influential dog than a clawless, toothless upright lion.