Presidential candidates will tell anyone who will listen that a state is important to their bids. If it's Iowa and New Hampshire, the state's historical role as an early barometer is crucial. If it's Nevada, for Democrats, the candidate wants to give Hispanic voters a bigger voice in the process. If it's South Carolina, it's important to let African American voters have a say, for Democrats, and to let a Southern state get in on the action, for Republicans.

But for the GOP, South Carolina is crucial for another reason: No Republican presidential candidate has ever won the nomination without winning the Palmetto State. This year, as former Massachusetts Governor Mitt Romney maintains leads in Iowa and New Hampshire, several other Republicans are hoping that South Carolina plays the same role in 2008 as it did for then-Gov. George W. Bush and Sen. John McCain in 2000: A bulwark where a surging candidate meets conventional wisdom and fades away, in favor of the eventual standard-bearer.

Those hopes appear to be working, at least so far. According to recent polls, Romney runs a distant fourth in South Carolina. The latest Real Clear Politics Average shows Romney, with about 10 percent, trailing former Senator Fred Thompson and former Mayor Rudy Giuliani, with about 22 percent each, and McCain, who clocks in at 14 percent.

To win in South Carolina, it takes organization in three major Republican regions. In the Low Country, along a coast populated with more non-natives, McCain came away with narrow wins in Charleston, Georgetown, Beaufort and Horry Counties. The region, some suggest, will provide Giuliani and McCain with the bulk of their votes this year, and makes up another fifth of the electorate.

The suburbs of Columbia, the state capitol and home to nearly a quarter of the Republican votes, are home to the state's oldest Republican enclaves. Franklin Roosevelt once won the state with 96 percent of the vote; now, the Up Country, as it's called, gave Bush his highest margins in the state.

But the real battle for the primary will happen in the Upstate, in the counties around Greenville and Rock Hill, in the northwest corner of the state. All told, the Upstate, from Greenville County through Spartanburg and into York County, will account for about 30 percent of the Republican electorate. The voters are "Bible-thumping conservative," former GOP consultant and Clemson Professor Dave Woodard said, and are the most easily attached to one candidate.

It is essential, many say, to win the area. Bush beat McCain about 59 percent to 35 percent in the Upstate, the highest margin he won in any of the state's regions, and sealed his victory in 2000. Any candidate who convinces social conservatives to come to their side can carry the state.

Unlike in Iowa, where Republican voters can be swung by issues like ethanol and farm subsidies, and New Hampshire, where the intensely libertarian electorate lives by the state's "live free or die" motto, South Carolina is the first time candidates face average conservative Republican voters. To win the state, say many former Palmetto campaign hands, requires a combination of a dedication to retail politics and a commitment to the South's traditional conservative orthodoxy.

Romney, who has spent a considerable amount of money in the state, has struggled to convince voters of his conservatism, thanks to several recent conversions he's undergone. Many social conservatives just don't trust Romney, and it's clear that Romney is not a Southerner. "He comes across as being over-coached, over-focus grouped in his language," said GOP consultant Chip Felkel. According to Woodard, there's another reason Romney hasn't connected: "Fred Thompson says 'y'all,' and Mitt Romney doesn't."

But others say Romney shouldn't be counted out yet. Romney "has flipped, if you want to call it that, or matured in these positions, but he hasn't changed back," said conservative activist Elmer Rumminger. "Reagan, for example, started off pro-choice."

Romney's other problem is that he enters the race little known compared with his rivals. McCain has run in the state before; Thompson is well-known thanks to his acting career and near-continuous buzz surrounding his entry to the race; and Giuliani's actions on and after September 11th have given him a reputation as a strong leader.

Starting from behind, Romney has built what is almost unanimously seen as the strongest organization in the state. His campaign boasts 11 employees in the state, and he's visited 14 times since 2007, according to the campaign.

Romney also retains a chance because conservatives have yet to coalesce behind a candidate. McCain's collapse nationwide has been felt nowhere as much as in South Carolina. Polls showed him leading by as much as 13 points, in late April. Now, said Felkel, "it would take a Lazarus kind of event to resurrect that campaign."

Still, the Arizonan whose hopes for the nomination died in South Carolina in 2000 maintains establishment support. The Speaker of the State House and the Attorney General both back him, as does the state's senior senator, Lindsey Graham. "We have the strongest organization of any campaign in South Carolina," said McCain spokesman Brian Rogers, who said, like Romney, McCain has 11 staffers working in the state and has been there a dozen times since January.

Since Thompson's name has been floated, Giuliani has experienced a downward slide as well. Polls once showing him in first place now put him tied or slightly trailing Thompson, and much of his support, some suggest, comes from residual good will from Sept. 11. "Rudy's personality, his tough-guy leadership, his determination are something that people admire," said one Republican who asked for anonymity to speak freely.

Giuliani will still need to convince conservatives that his positions on gun rights, gay rights and abortion are nothing to worry about. So far, he has not let what might ordinarily be deal-breaking positions to derail his candidacy. "He's been able to sort of stiff-arm the abortion and gay stuff a little bit by taking a federal approach to it," said Francis Marion University Professor Neal Thigpen, referring to Giuliani's stated preference to leave social issues up to the states.

But the pass Giuliani has gotten so far is unlikely to last. "The question is, what happens when the attack ads come out?" asked the Republican. "What if a third party out there starts talking about the Mayor's three marriages?"

Thompson, who should have been able to capitalize on the faults of other front-runners, has been hurt by his late, and some say bumbled, entry. "There's a lot of sentiment out there for him," said Thigpen, though it isn't organized in the way necessary to win. "He's going to have a hard time getting a ground game put together."

His late start, after dabbling for such a long time, will hurt him, said Rumminger. "He doesn't seem to have a good grasp of the issues," he said. "The honeymoon is pretty well over."

The honeymoon is important to winning South Carolina, as voters here are less needy than those in other early states. "South Carolinians are not like Iowans and people in New Hampshire," Felkel said. Iowans and Granite Staters "want to be feted and courted and hailed down upon," he said. "South Carolina likes to get involved, but it doesn't consume the state."

Whoever is on a roll when Palmetto voters cast their ballots, and whoever has built a strong enough rapport with social conservatives, will come away with a South Carolina win. History, though, predicts that candidate will win much more than just South Carolina.