Not surprised that they wouldn't bother with this debate, why be part of yet another debate where you can only answer in sound bites and viewership will be limited. And why participate knowing you might get beat up by the religious right for not being conservative enough?
Republicans participating include Sam Brownback, Mike Huckabee, Duncan Hunter, Ron Paul, Tom Tancredo and John Cox. Candidates who declined are Rudy Giuliani, John McCain, Mitt Romney and Fred Thompson.(via)
BTW, Alan Keyes will be there since he's now entered the race. Just what the race needed, yet another conservative candidate to split the conservative vote and insure that Giuliani gets elected.