presidential hopefuls are pulling punches, primarily directed at front runner mitt romney.but as joe johns explainsney is fighting back as ell. --reporter pkg-as follows --in the home stretch to the first in the south primary..the urgency of the moment finally starts to show. newt gingrich.. looking strong late in the race..was back to making bold predictions again. "if we carry saturday, i think i will become the nominee"and then this prediction that the race in south carolina was about to take a turn for the worst."i fully expect thh romney campaign to be unendingly dirty and dishonest for the next fouu days because they are desperate thhy thought they could buy this." to get the nomination, gingrich has to go through the frontrunner; mitt romney...who was hammering away at gingrich's leadership skills both in new web ads and a telephone conference call featuring republican members of congress who served with gingrich back in the day. the former massachusetts governor went after gingrich on the stump too...treating him very much like the last man standing between romney and an acceptance speech a

joe johns, we keep hearing about this super pacs. explainthe help of the super pac. >> reporter: it's all about the money. when you have a guy like sheldon aidle son, the billionaire who's kicked in big money to the super pac, or the father of jon huntsman, who's also kicked in money to his pro-huntsman super pac. this money goes in and gets spent supposedly independently on television ads that go all over the place. they really keep the campaign running. donors then give to the campaign to support the candidate, so that's the bottom line. it's all about the ben mince, as they say. >> all about the ben mince, baby, but there is some gray work. as it happening, last night stephen colbert announced he'll run for office. so supposedly signing over his super pac to comedy central's jon stewart. here's the exchange they had with a former government lawyer. >> now that i have the super pac, can i run ads supporting stephen colbert, who i believe in very deeply, perhaps attacking his potential opponents? >> i don't believe in it at all -- >> yes, y

john. >> joe, as you know, speaker gingrich runs his own campaign. he's the top strategist, scheduler and so forth. two very energetic, passionate debates in south carolina. how do they explain two definitely flatter and less combative performances that may have hurt him in florida? >> reporter: i've asked the campaign that. they don't have much of an answer for that. in fact the answer i got from them was that in their view romney was untruthful on several occasions during this debate, and newt gingrich felt as though if he addressed some of these things he would have appeared as if he had been nitpicking during the debate. they did put out an ad to try to address some of the things they think were untruthful. but it's quite clear that yesterday during the day newt gingrich was very energetic, very much on the attack, and then when he hit the debate he seemed just a little bit flat, john. >> joe johns tracking the gingrich campaign tonight live in florida. >>> republican presidential candidate ron paul has repeatedly denied any role in writing racist newsletters published in his name in the 1990s. the "new york post" quoted several ron paul associates who said he did sign o