One of the things I've always liked about Arlen Spector is that he--as distinct from almost everybody else in politics--doesn't really care whether you like him or not. He knows that he has to find allies, to identify common interests, to make details. And he certainly enjoys power: he doesn't have much doubt that life would be better for everybody if he were in charge. He certainly feels (and not without reason) that he is, if not smarter than most people, then at least better informed and harder working (and maybe smarter, too). But he's refreshingly lacking in that narcissism that can be the defining feaature --and the bane--of lesser and even greater men.
No surise, then, that he had the chutzpah to jump ship on the Republican party when he figured he couldn't deal there any long, full well understanding (as he must have understood) that he would outrage his old allies and not win a lot of applause from his new. Consistent with this view, a large part of me wants to say: go for it, ol' buddy. Make the deals you can, recognizing (as you surely recognize) that you face a new set of demands which require a different calculus.
But there is anothere issue that isn't necessarily captured in the old loyalty-betrayal stuff. Put it this way: Arlen Spector is not the indispensable man. Pennsylvania does not need to have him as senaator: they've survived worse and they've enjoyed better. Or even if not better, at least different. "Different" meaning able to respond to new challenges in new ways. Arlen, you've been in the Senate since 1960. Per Wiki, you are the 12th in Senate seniority, and fifth oldest. Aaron Schock, the Republican Congressman from Peoria, wasn't even born when you took your seat. Life will go on when you are pushing up daisies--even when you are just out to pasture, and watching the daisies grow.
They say that Joe Sestak is flirting with the idea of a primary run against you. It's a remarkable race where a retired rear admiral will qualify as "young:" Sestak was born in 1951, the year you got your Phi Beta Kappa from Penn. Is Joe Sestak the right man for Pennsylvania? Hell, who knows? Certainly not I, who have never paid attention to him until just now. And is there ever a right man, except in the eyes of the man himself? But it's time to go, Arlen--not for your skills at betrayal, in an institution where (as you rightly understand) loyalty never counted for much. And not because you weren't good at what you do. But nobody is indispensable. Arlen, it's time to go.