With statements like this, he deserves to lose the primary. He got elected in 1988 with the support of the RNC, he spouted off right-wing talking points during the 2000 recount, and now he won't rule out leaving the Democratic party. Time to show him the door. He's not a team player.
Government service is not about being a "team player." You're sent to represent your state, not some party.
In any case, I think Joe should jump from the Dems and become an independent now. It would be nice to see another (I) in congress. Hell, it would be nice if they were all (I).