Evangelicals make up 40 percent to 50 percent of South Carolina's population, according to the Pew Forum on Religion and Public Life. Collectively, the Christian conservatives showed their strength in 2000, when they backed George W. Bush over John McCain — reversing the momentum in that year's race.
But South Carolinians do not always vote as a single bloc or at the beckoning of a single candidate. In 1988, for example, the evangelical Rev. Pat Robertson came in third in the state's GOP primary, behind then-Vice President George H.W. Bush and then-Kansas Sen. Bob Dole.
Instead, the state's Christian conservatives are moved more by issues such as abortion, stem-cell research and same-sex marriage, says Clemson University political scientist and former GOP consultant J. David Woodward.
Powerful outside groups such as the South Carolina Citizens for Life and the National Rifle Association have been adept at fundraising and reaching out to potential voters, Woodward says.
In recent decades, religion has been less of an overt touchstone for Democratic candidates, who have not made the same religious appeals as their GOP counterparts. But religion remains an important undercurrent in the Democratic race, since the candidates often hold events in African-American churches and with African-American religious leaders, says John Greene, a senior fellow with the Pew Forum on Religion and Public Life.