At a forum hosted by Mike Huckabee with 800 undecided South Carolina Republicans, Newt Gingrich was loudly booed when he criticized Mitt Romney's record at Bain Capital, according to a Republican who attended the closed-press event.

"They were really angry," said the attendee. The forum will be aired on Fox News tonight.

The booing came when Gingrich mentioned Romney's name. I am told Gingrich was gently reprimanded by Huckabee who reminded him that the ground rules for the forum stipulated that the candidate were not allowed to attack each other.

Every candidate except for Ron Paul took part in the forum, each of them appearing separately.