With the polls closing just a short time ago in South Carolina, news organizations are projecting that former congressman Newt Gingrich has won the Republican presidential primary.

The primary was seen as essentially a two-man race – Newt Gingrich and former Massachusetts governor Mitt Romney.

Just a week ago, it appeared Romney, who won last week's primary election in New Hampshire, would win easily in South Carolina.

But Romney, a multimillionaire investor, has struggled in recent days following questions about his personal wealth, and his acknowledgement that he pays taxes at a much lower rate than most Americans.

Gingrich, meanwhile, surged in the polls after two well-received debate performances.

The two other Republican contenders, former Pennsylvania senator Rick Santorum and Texas Congressman Ron Paul, are expected to battle for third-place.