Columbia, S.C. -- The polls are open across South Carolina and close at 7 p.m. Here are five things to watch in today's Republican presidential primary.

  1. How quickly do The Associated Press and the major television networks declare Donald Trump the winner tonight? That happened moments after the polls closed in the New Hampshire primary on Feb. 9 and could happen again tonight. If it doesn't come quickly, we could be in for a shocking night.

2. Who claims second place? Trump has led the polls here for months and is expected to finish first. But the race for runner-up is perhaps more important. Texas U.S. Sen. Ted Cruz has held that spot in most polls, but Florida U.S. Sen. Marco Rubio could see a boost from Gov. Nikki Haley's endorsement this week.

3. Do Ohio Gov. John Kasich and former Florida Gov. Jeb Bush survive? Both candidates have polled anywhere from third to fifth in recent weeks and anything less than a third place finish could be devastating. Bush, in particular, seems to need a strong showing here after deploying both his brother, former President George W. Bush, and his mother to campaign for him.

4. Watch the Upstate, the Pee Dee and Lexington. In the Upstate -- think Greenville and Spartanburg counties -- evangelical voters have great influence. In the Pee Dee, especially Florence and Horry counties, are home to strong contingents of Tea Party voters. Lexington County, in the Midlands, is another major Republican stronghold. All will have major influences on tonight's outcome.

5. Turnout is expected to be high. Polls are already busy across the state and nearly 60,000 absentee ballots were cast in advance. The weather is expected to be sunny and warm -- a sharp contrast to the cold rain that fell most of the day four years ago here when Newt Gingrich won the 2012 primary.