The early exit poll, over 2000 respondents, has Trump up by 4.5 percent over Cruz and by 7 over Rubio. Bush, Kasich, and Carson are all in the single digits.
If the results bear this out, then expect Cruz to challenge for some delegates in CDs 4, 5, and 7, and Rubio to challenge in CD 1. But South Carolina is winner take all at all levels, so any statewide win will give Trump 29 delegates. The winner of each CD will get three delegates per district.