CHARLESTON, SC.--The final GOP debate before the Saturday primary in South Carolina starts at 8 p.m. est on CNN and the pressure is on frontrunner Mitt Romney not to make a mistake--potentially compounding the difficult week he's had.

To watch for:

1. Does Romney do a better job of explaining his personal tax "15 per cent rate" situation.

2. Does Romney do damage control over saying that his $374,327 in speaking fees is "not very much."

3. How will Romney react if Gingrich releases his income tax return before or during the debate--and Romney only grudgingly said he would release only the latest year in April--after crucial early state primaries.

4. Does Romney do a better explanation and defense of running Bain Capital, the investment firm.

5. Does Romney underscore his solid family life--without looking as if he is trying to exploit interviews Newt Gingrich's former wife Marianne is giving--out Thursday--about how he wanted an open marriage while having an affair with Calista, his current wife.