I find another series of events most enlightening when thinking of this. Remember, Sue Collins? She is one of two GOP senators from Maine. She voted for Obama's stimulus package and what credit does that earn her? None, in fact if you google "Sue Collins flu" you see a series of leftist blogs with identically named posts, what do they call that when they hallucinate right wing blogs doing the same? Oh-yeah echo chamber. That is to say, Sue Collins is called to task on a stupid and silly point that should equally apply to Charles Schumer but, since Sue is a Republican in good standing she gets hammered for it. Remember that Sue & Olympia, your Dem friendly votes do not get you any brownie points.
However, since Spector is now a Democrat he is being lauded as a moderate. While I don't get too worked up by such calculations, Spector is not a moderate (ironically he is farther right than Liebermann who is all but persona non-grata with the left because Lieberman is moderate on only one issue and supported McCain's presidency bid), Areln Spector is an opportunist. His sole motivation for bolting the GOP is the same as Michael Bloomberg's for bolting the Democrats they would lose their nomination fight in the primary.
In any event Arlen Spector the hammer of Hill has his nomination in the bag, this will be a big test of the how long President Barak's coattails are.