Arlen Specter: Principled or Sore Loser?

Yesterday 79 year old Arlen Specter, Senator from the commonwealth of Pennsylvania, left the republican party to become a democrat. This shortly after telling Newsweek that he would not. If Senator Specter was doing this out of principle, I would applaud the move. I believe that our elected officials must lead based on principle. While I may not agree with the principles that particular people have, I, at least, will respect that they are doing it based on their value system.
Senator Specter has shown none of that in the past few days. The polling showing him losing badly to Pat Toomey is the reason for his departure of the GOP. Doesn't this just make him look like a man who can't handle losing? What is so unbelievable is how easily he admits it. Just flat out says that he can't win as a republican, so hey, what the heck, I am not ready to retire so I am going to walk away from my principles and do whatever is needed to win.
I am having a hard time understanding why he just didn't go through the primary process and run as an independent if he did indeed lose the nomination. It worked for Joe Lieberman, Independent Senator from Connecticut. While I don't promote that activity, it makes more sense than just up and leaving your party for nothing more than self-serving purposes.
How can anyone trust the man from this point forward? What will stop him from making a realization after getting elected that he did the wrong thing and want to go back to the republicans? I doubt they would want him back after this, but all the same, it could happen. I don't live in Pennsylvania, so I have no say in how this turns out. But one must admit, it is going to be a fun election to watch.