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Fred Thompson visited a gun shop in South Carolina on Tuesday.

COLUMBIA, South Carolina (CNN) – Fred Thompson stood in the middle of a gun shop in Greer, South Carolina on Tuesday, trying to sum up the Republican race for the White House.

"It's a very fluid situation," the former senator said. "As far as I'm concerned its up to the Good Lord and the American people, and that's just fine with me."

But probably not even the Lord himself could have predicted the Republican race here would be this wide open this late in election season.

South Carolina, a crucial test of a candidate's conservative mettle, has voted for the eventual GOP nominee in each election since the state's primary began in 1980.

Like the national contest, the Republican race in the Palmetto State is essentially a free-for-all, with no candidate able to solidly break free from the rest of the pack .

An AP/Pew poll of likely Republican voters released this week shows a three-way dead heat for first place in South Carolina, with Thompson coming in at 18 percent, just one point behind former Massachusetts Gov. Mitt Romney and former New York City mayor Rudy Giuliani, who are tied at 19 percent.

Nipping at their heels and still very much in the race are Sen. John McCain, at 13 percent, and the up-and-coming former Arkansas Gov. Mike Huckabee, at 10 percent. Rep. Ron Paul, who has sent out at least six glossy direct mail pieces in the state in recent weeks, comes in at six percent.

On top of that, support is soft: just 44 percent of GOP likely voters said they "strongly support" their choice.

"There are probably going to be two winners here, because I don't see that big of a thread between any of the candidates," said Katon Dawson, chairman of the South Carolina Republican Party. "It's going be a rough and tumble brawl. It's going to be tough."

The only certainty in the race seems to be that things will remain uncertain.

George W. Bush's lead in South Carolina evaporated overnight after McCain won New Hampshire in 2000. McCain and Bush competed in the following weeks to win over South Carolina voters, but McCain notoriously lost that contest after a largely-anonymous serious of slanderous attacks derailed his bid.

With the primary date set for Jan. 19, just over a week after the New Hampshire primary on Jan. 8, the window for a candidate to differentiate himself is now even smaller than it was in 2000. South Carolinians may get saturated with television ads shortly after the New Year as candidates jostle for position in such a short period of time.

"Christmas is coming up, there's going to be some bowl games, and politics will be on the backburner except for in the mail," Dawson said. "As soon as Santa Claus comes down the chimney and leaves, here come the candidates."

But unlike the Democratic candidates, who are overwhelmingly focusing their campaign stops on Iowa, Republicans have already made time for South Carolina. Since Thanksgiving, McCain, Giuliani, Paul, Huckabee and Thompson have all campaigned in the state.

Only Romney has not visited in recent weeks, but is still running strong thanks to non-stop TV ads and a barrage of direct mail pieces.

Romney long held significant leads in Iowa and New Hampshire, but faced low expectations in conservative South Carolina because of questions about his Mormon faith and his past support for abortion right and gay rights.

Romney's lead in those states is shrinking, but in South Carolina, Romney is now a bona fide frontrunner. However, as is the case in Iowa, one of Romney's most cash-strapped opponents could pose the biggest challenge: Huckabee.

The Sunday after Thanksgiving, Huckabee paid a visit to the state and slipped easily back into his old ministerial role, giving two sermons at different Baptist churches in South Carolina, telling one congregation, "The only good thing about any of us is the God in us."

At First Baptist church in Fountain Inn, churchgoers waited in line for nearly an hour to shake his hand after the service.

Contrast that eagerness with comments from Robert Taylor - a dean at Bob Jones University who has endorsed Romney - who told a closed-door audience of the school's students and alumni in November: "I think there's a lot of us evangelicals that have kind of held back a little" with Romney because of his faith.

Even Sen. Lindsey Graham, a die-hard supporter of McCain, admitted Tuesday that, "what you see nationally with Huckabee is happening in South Carolina."

(Although the AP poll shows Huckabee at 10 percent, the poll's sample period began nearly a month ago, before Huckabee's recent surge in media attention.)

McCain has taken an aggressive posture on the campaign trail, not shying away from drawing contrasts with his opponents. He sent out a mailer here in October criticizing Giuliani on his support for abortion rights, and he has begun to hammer his rivals for lacking foreign policy and military experience.

This time around, McCain also has a long list of endorsements, the kind of institutional support he lacked in 2000.

However, in South Carolina, immigration continues to be McCain's Achilles' heel.

At any given campaign stop in the state, if a candidate takes five questions, two or three of those will almost certainly be about illegal immigration, and McCain gets plenty.

But the majority of McCain's campaign stops take place in friendly territory, where he gets a hero's welcome - at VFW and American Legion Halls, or in the coastal areas populated by veterans where McCain performed well in 2000.

McCain's biggest challenge in those areas may come from Giuliani. The mayor, his lead bolstered by his national fame and name recognition, appears in South Carolina slightly less often than other candidates but likes to visit booming coastal communities heavy with retirees, many of whom moved to places like Hilton Head from his native New York.

Giuliani even brought along the gruff New York congressman Peter King for a recent campaign stop at a retirement community in Bluffton, with Giuliani touting their shared Brooklyn roots.

Unlike McCain, Giuliani has recently stayed away from Greenville and Spartanburg in the opposite side of the state, dominated by religious conservatives and much of the state's business community, although his campaign recently opened a new office in Spartanburg.

Oran Smith of the Palmetto Family Council, which is affiliated with James Dobson's group Focus on the Family, said Giuliani seems to campaign in the state less than the other candidates and has been "crowded out" by voters looking for a "true conservative."

"So many now are focusing on people they think are more in line with their values, but can win," he said. "So you've got Romney and Thompson vying for that "conservative who can win" label, and all of a sudden here comes Huckabee."

Thompson is often criticized for running what some say is a lackadaisical campaign. But Thompson answers his critics by routinely citing his strong poll numbers in the state, and the Tennesseean likes to say "it's good to be home" when campaigning down south.

Despite the national criticism, Thompson draws strong crowds in South Carolina and seems to thrive in smaller meet-and-greets, where he jokes about college football and southern food while touting his "consistent conservative" message, frequently criticizing Romney for changing positions on abortion.

Besides Romney, Thompson is the only Republican to run television ads in the state.

But now that the holiday season has arrived, observers say, South Carolinians are more likely to pay attention to commercials from Best Buy or Target than to ads talking immigration and taxes.

With those distractions, the race's outcome will likely remain murky until primary voters actually show up to the polls in January.

– CNN South Carolina Producer Peter Hamby