With unemployment and anti-immigrant sentiment on the rise, Huckabee, one of two Southerners in the race, has pulled even with McCain, according to the latest polling. The Arizona senator had led here since his victory in New Hampshire this month.
"Being in South Carolina is like being at home," Huckabee tells voters here. "You folks know how to eat catfish and grits, and [we] talk the same language."
So does Fred Thompson, from Tennessee. But he's running far back, despite pouring everything he's got left into this state. Without a victory or close second-place finish today, it will be the end of the trail for the former senator and actor, said a top aide.
Mitt Romney also lags badly, despite airing as many TV commercials as the rest of the field combined. Romney left earlier in the week for Nevada, where his only competition in today's caucuses is Ron Paul.
Democrats, whose South Carolina primary is a week away, are also holding caucuses in Nevada, where Hillary Rodham Clinton and Barack Obama are in a close race.
For Republicans, this weekend's main event is South Carolina, a bellwether over the past quarter-century. Reflecting, in part, the South's dominance during the Reagan-Bush era, every winner here since 1980 has become the Republican nominee.
In 2000, this state was the turning point in George W. Bush's fight with McCain, but this time, much of the party establishment is with McCain. So are former Bush voters such as Jimmy Evans, who sells real estate in Columbia, the state capital, and who counted the late Strom Thurmond as a personal friend.
The 65-year-old finds a lot to like about all the contenders, including Huckabee, but thinks McCain would make the best commander in chief.
"If you can't pass muster on foreign policy," said Evans, "nothing else matters."
McCain's chances will depend, to a large extent, on whether voters are more concerned about fighting Islamic extremism abroad than outlawing abortion and gay marriage and deporting illegal immigrants.
Huckabee is targeting voters who are feeling the pinch of a weakening economy and a jobless rate that is the fourth-highest in the nation.
Paul Cockrell, 54, of Gilbert, S.C., said he recently quit the heating and air-conditioning business, where competition from companies that employ Hispanics is costing jobs.
Cockrell wants a presidential candidate who will "start deporting the lawbreakers." After concluding that McCain "doesn't get it," he's leaning toward Huckabee.
The former Arkansas governor, once criticized for proposing to give in-state college tuition to illegal immigrants, is appealing for anti-immigrant votes with implicit criticism of McCain, telling Carolinians that a vote for him will "send a message" to Washington.
"They've had their chance," Huckabee told supporters in Lexington, a fast-growing Columbia suburb. "They still haven't secured the borders. Let's make the American economy work for Americans, rather than for somebody halfway across the globe."
As he did in winning Iowa, the ordained Baptist minister is counting on support from religious conservatives in a state where Southern Baptists are 40 percent of the population and evangelical Christians may cast two of every five primary votes.
Huckabee is again running TV commercials that label him a "Christian leader" (a line he dropped in New Hampshire), and he met privately this week with a group of ministers.
The Rev. Thomas S. Hart, pastor of the Living Word Assembly of God church in Lexington, S.C., said Huckabee "has got more support than the polls are showing." Electing the first preacher-president since James A. Garfield would guarantee that "America will be blessed, and God will intervene" on the nation's behalf under a Huckabee administration, he said, offering scriptural references to bolster his point.
Jenny Martin, 27, a stay-at-home mother with 2-year-old twins and a baby due next month, said she and her husband are doing everything they can for Huckabee.
"We love the fact that there's a Christian running for president," said the self-described "values voter" from Irmo, S.C., who added that she cares about lower taxes, smaller government and fixing the immigration problem, as well as "pro-family issues" and ending abortion.
A prediction of bad weather throughout the state today is making political forecasting extremely hazardous, but some think the wintry conditions will help Huckabee.
"If it's raining, if it's cold, I put less money on" McCain's voters turning out "than I put on these evangelical Bible thumpers. They're going to be there," said Neil Thigpen, a McCain supporter and a political scientist at Francis Marion University in Florence, S.C.