Why Is The GOP Shunning Its Own Republican Candidate for Senate in Connecticut?

President Bush has come out and said he will not support his own party's candidate for the U.S. Senate seat in Connecticut currently held by Joseph Lieberman who went Independent after he was defeated for the first time in the Democratic primary vote in early August. Clearly, all the big GOP cheese like Karl Rove and Ken Mehlman are also throwing their weight behind Lieberman. So what's behind the shunning and ostracization of Lieberman's GOP adversary by his own party?