State: South Carolina
Type of election: Primary
How it works: South Carolina is a pretty standard primary. Independents are allowed to vote in either primary and are expected to participate in relatively high numbers in the Republican primary.
Official election results: South Carolina State Election Commission
Republican candidates: Newt Gingrich, Ron Paul, Mitt Romney and Rick Santorum (all others have dropped out or are polling at less than 1 percent)
Democratic candidates: Barack Obama
Previous performance: In 2008, Romney finished fourth in the Republican primary to John McCain, receiving 15 percent of the vote. Paul finished fifth with 3.6 percent. Obama won the Democratic primary with 55 percent.
Television stations: Full list
Latest polling: Most recent from each polling organization:
Nate Silver gives Gingrich a 82 percent chance of winning, followed by Romney at 18 percent. All other candidates are at 0 percent chance to win according to Silver.
Wild card: Stephen Colbert and Herman Cain have been having fun with South Carolina. Will voters take them seriously enough to affect the outcome? Probably not.
Bottom line: A Romney win pretty much seals the deal for him, since his major opponents have, for a while, put everything into South Carolina. A victory by Gingrich could propel him to front-runner status, but it remains to be seen if he has the infrastructure or money to compete in upcoming states. It's hard to see how Santorum stays in if he finishes in an expected fourth place.