By Wolf Blitzer, CNN
(CNN) - And now there are four Republican presidential candidates left in the contest.
They were all on the stage Thursday night at the tough CNN debate in South Carolina.
One of them will almost certainly face President Barack Obama in November. There is still a tiny chance no one will emerge with enough delegates to wrap things up. I suppose, at least theoretically, there could be a brokered convention in Tampa, Florida, at the end of August.
The president shows off his singing skills at campaign events. CNN's Wolf Blitzer has more.