Q: Can Gingrich keep up his momentum?
A: The former Speaker is often his own worst enemy, particularly when things are going well. His bombast tends to spill over into arrogance, he is famously undisciplined. But he is channelling the anger of the social conservative and Tea Party wings of the party like no other Republican candidate. "At least Newt's a fighter," is the constant refrain of party activists, yearning for a truly aggressive candidate to take on Barack Obama.
Helping him has been the unprecedented importance of the debates. These play to his strengths: an ability to think on his feet and a gift for the cutting soundbite. There will be two more next week in Florida. But Mr Gingrich trails Mitt Romney in money and organisation, and will rarely encounter such favourable terrain as South Carolina. He is also the candidate with the most "baggage", not just his two divorces, but a dodgy ethics record in Washington. The longer the campaign lasts, the more these factors will weigh against him.
Q: Can Romney recover?
A: Yes, but he will have to show a quality Mr Gingrich has in abundance – fight. Few nominees don't have a scare along the way, and if Mr Romney does prevail, this will have been his. But South Carolina demonstrated all his weaknesses, which will not be easily cured. Religious and Tea Party conservatives do not trust him, believing he is not one of their own.
Mr Gingrich has a raw naturalness about him. Mr Romney seems robotic, over-cautious and over-programmed. The debates, where he does not shine, only underline this difference. He finds it hard to connect with voters – especially on matters of money, most notably his inexplicable stalling over releasing his tax returns. He remains the favourite for the nomination. First, though, he must take the battle to Mr Gingrich directly.
Q: Might a new Republican enter the race?
A: Unlikely, but if Mr Romney loses in Florida, a less conservative state than South Carolina, then all bets are off. The idea of Mr Gingrich as a nominee horrifies swaths of the party establishment, which regards him as unelectable, and has long since lined up behind Mr Romney.
Expect calls to go out to potential white knights such as Jeb Bush, Mitch Daniels or Chris Christie, imploring them to change their minds and jump in, amid fanciful scenarios of third candidates and brokered conventions. But such a manoeuvre would risk enraging activists and further dividing the party. The big winner would be Barack Obama.