Why Doesn't He Become a Republican?

Joe Lieberman ran on the Democrat ticket in the last election and has been an "independent" ever since. This news item is about his non-attendance at Democrat lunches. Why SHOULD he attend their policy lunches? After losing the vice-president spot as a Democrat, the Democrats "excommunicated" him. So he ran for re-election to his old Senate seat as an independent, and WON. They couldn't beat him then and they can't beat him now. Why he doesn't just become a Republican, I don't know. We could use one more vote in Congress. But for some reason, he refuses. Maybe one day we'll find out why. (Yahoo News)