Pawlenty, Gingrich, Santorum, Roemer, Paul are on the list now. Romney has not made a commitment. I suspect others might join, the deadline for proof is May 3rd. (I would secretly like to see Palin and Trump in this. This would be a great reality-your fired show. Saturday Night Live would have a great source for comedy skits.)
The debate is being held in South Carolina at 7:00, I suspect we will see it at 5:00 mountain standard time.
FOX news is the the host.