Sioux City, a meatpacking hub on Iowa’s western lip, hosted the latest Republican presidential debate on Thursday. Upbeat supporters packed the downtown convention center, cheering the contenders. But the real drama, according to Iowa politicos, was not onstage but in the small towns scattered along the two-lane highways nearby, where thousands of flinty conservatives remain undecided.

During the 2008 cycle, western Iowa boosted Mike Huckabee, the former Arkansas governor and Baptist minister, who won the caucuses against better-financed competitors. This year, Mitt Romney and Newt Gingrich may lead statewide polls, but GOP operatives see four candidates — Rick Santorum, Michele Bachmann, Rick Perry, and Ron Paul — with the potential to surprise on a cold January night.

“They call this area God’s country for a reason,” says Chuck Laudner, a Santorum adviser and longtime strategist for Rep. Steve King, the tea-party favorite who represents the region in Congress. “These voters are Christian, constitutional conservatives. They know what they want, they’re like–minded, and they organize themselves, paying little attention to television ads and campaign maneuvers.”

More important to western Iowa conservatives is the personal interaction they have with candidates. The importance of one’s ground game has diminished elsewhere in the state, due to online outreach, but in the sparsely populated counties hundreds of miles from Des Moines, “it’s still about word of mouth, neighbor to neighbor,” Laudner says. “This isn’t the hinterlands, but people do things their own way.”

Perry, for his part, is cognizant of the region’s sensibilities and has spent much of this week on a bus tour, stopping in Council Bluffs and Storm Lake, along with a handful of western Iowa hamlets. His advisers see opportunity here, and his television ads, which focus on his Christian values, are part of his attempt to climb back into contention, fueled by a grassroots, anti-establishment western bloc.

“This was a natural place for us to start our final push,” says Bob Haus, Perry’s Iowa campaign chairman. “His roots, coming from the Texas farmland, help a lot. One of his clear strengths is retail politics, one-on-one campaigning, and that’s what people in western Iowa expect.” Perry’s “deep faith,” he says, is another factor, especially in a region that is home to many religious conservatives and evangelicals.

Rep. Michele Bachmann (R., Minn.), who won the Ames straw poll in August, is also paying close attention to western Iowa, and has visited the area frequently this fall. She begins her 99-county bus tour of the state in northwestern Iowa this weekend, starting in Sioux City and then heading south to Denison. But her advisers note that she is more than a western wooer — she plays statewide.

“Western Iowa is very important,” says Brad Zaun, an Iowa state senator and Bachmann confidant. “We’re keeping in touch with our people in the west, with those who helped us win the straw poll, which was our dress rehearsal, so to speak.” The campaign “has an infrastructure” beyond the bus, and Bachmann, he predicts, “will finish strong” after making stops at diners, town centers, and churches.

Santorum’s campaign, however, may be the one to watch in the west, since the former Pennsylvania senator has focused for months on the Hawkeye State and its western outposts. Rival GOP campaigns acknowledge his prowess, and even though Santorum is operating on a shoestring budget, they say he could be well positioned, should voter turnout be low, to mount an eleventh-hour surge.

“It’s a hard guess to say who’ll win in western Iowa,” says King, who has represented the region on Capitol Hill since 2003 and has yet to endorse. “It’s likely that Rick Santorum is connecting the most in the area. But that support could be adjusted somewhat by the practical nature of conservatives,” who may rally for Santorum, then decide to vote for a more competitive candidate in January.

“In the 32 counties that I represent, it’s an incredibly solid group of people,” King says. “Up in Sioux County, that’s the best Republican county in America. It’s a county where Steve King can carry 91 percent of the vote. That’s very Republican, conservative country. They are constitutionalist, pro-life, pro-marriage people.” The caucuses in the west, he says, are busy affairs; while they may have lower turnout than the “Golden Circle” region in central Iowa, they have more enthusiasm.

“Generally, western Iowa is won by a more socially conservative candidate,” says Steve Grubbs, a former state GOP chairman who recently directed Herman Cain’s Iowa campaign. “This year it wouldn’t surprise me if someone like Rick Santorum or Michele Bachmann did unusually well. It’s going to be tougher ground for Newt Gingrich or Mitt Romney. The region is very agrarian and has somewhat of a libertarian streak, an independent spirit, and that doesn’t fit every candidate.”

And for that reason, Rep. Ron Paul (R., Texas) sees hope in the west. His campaign has dispatched volunteers to western Iowa, launching various get-out-the-vote initiatives that they bet will connect. “We’re following the traditional model because it works,” says Drew Ivers, the campaign’s Iowa chairman. “Ron Paul is definitely for real out here,” adds Tim Albrecht, the communications director for Iowa governor Terry Branstad. “He is going to get 18 percent in the caucuses no matter what. If there’s a snowstorm, he’ll probably win.”

But don’t underestimate Romney’s chances. According to a Rasmussen poll released on Thursday, the former Massachusetts governor, with a strong close to his caucus campaign, could improve on his 2008 performance, when he placed second. Per Rasmussen, Romney has 23 percent support, three points ahead of Gingrich and five points ahead of Paul. Perry, Bachmann, and Santorum are at 10 percent and lower, but each has improved since Rasmussen’s November survey.

Sources close to Romney’s Iowa team say the campaign’s volunteer network from four years ago will be an asset as other candidates hit the road. In 2008, Romney was not able to fend off Huckabee in most western areas, but in well-populated Woodbury and Pottawattamie counties, Romney won. This season, Romney backers are not predicting a repeat performance, saying things remain fluid.

GOP operatives unaffiliated with the Romney campaign tend to agree, arguing that Romney could emerge from a crowded field with a victory, and that Bachmann and Perry, though comfortable fits for western voters, do not have sprawling, well-financed political operations, leaving the west wide open for either a Santorum stunner or a Romney plurality, even in the state’s deep-red farming towns.

Gingrich, of course, also lacks much of an organization, since his rise in the polls was sudden and fueled by national momentum, not early-state groundwork. He rose to the top of state polls in November, but in the new Rasmussen poll, there are signs of trouble, with his total dropping 12 points in one month. On the trail this week, Gingrich played down expectations. “I think Iowa is going to be a challenge,” he said, with all candidates “firing away in a relatively small market.”

Gingrich’s Iowa advisers, who have quickly built a state team, tell NRO that the former speaker should not be counted out. “There are more Republicans in western Iowa than in any other part of the state,” says Katie Koberg, a Gingrich aide. “Our big mission is to make sure Republicans don’t stay home on caucus night.” With their website and telephone town halls, “we have been able to connect with voters.”

Indeed, every campaign is scurrying, and with less than three weeks until the caucuses, western Iowa remains the must-watch variable in the Iowa calculus. “We’re more conservative than any other part of the state,” King says. Among the cornfields, “far away from government services,” Republicans are “self-reliant, they work the land, and they’re looking for a candidate who shares those values.”

— Robert Costa is a political reporter for National Review.