Des Moines, Iowa — On a blustery New Year’s Day, Rick Santorum was in the rural, western slice of the Hawkeye State. He spent the morning at the Daily Grind coffee shop in Sioux City, and then held a rally in Orange City. In the evening, he drove north to Rock Rapids, a sparsely populated town near the Minnesota border. As expected, the road trip drew heavy media coverage. But Santorum was looking for more than the spotlight; he was scrambling for votes. As Tuesday’s caucuses near, the former Pennsylvania senator is surging, but his momentum is precarious, fueled by a finicky Iowa electorate. To bolster his chances, Santorum had to head west, to the state’s conservative hotbed, where hundreds of farmers and meat packers may determine his fate.

Four years ago, Mike Huckabee rode his support among evangelicals in western Iowa to a surprise caucus victory. Santorum, a Roman Catholic with close ties to politically active Christians, hopes to do the same. “That’s why he’s up in the northwest corner, God’s country,” says Chuck Laudner, Santorum’s Iowa strategist. “That’s the first spot on the Iowa map where Senator Santorum found a foothold.” Indeed, since discovering “pockets of support” in the area months ago, Santorum has visited repeatedly, stumping for hours in little-known hamlets, Laudner says. From shaking hands in supermarket parking lots to pitching pastors in their homes, intense retail politicking has been the strategy. With few dollars to spend, it’s also a necessity.

For a while, it seemed like the hard work would never pay off, and until early December, Santorum lingered in the low single digits of Iowa polls. But now, in a state where the small things matter, Santorum is poised for a major political upset, mostly because of his diligent, low-key hustle. The evidence of his potential is plentiful. According to the latest Des Moines Register poll, Santorum is in third place, with 15 percent support. That’s nine points behind the poll’s leader, Mitt Romney, and seven points behind Ron Paul. But in the final two days of polling, Santorum moved into second place, a mere three points behind Romney. And among evangelicals, Santorum has catapulted into first place, garnering 25 percent support. He also leads, tellingly, among likely caucus-goers who describe themselves as “very conservative.”

“Right now, timing is everything and Santorum has it,” says Steve Grubbs, a GOP consultant who recently directed Herman Cain’s Iowa campaign. “He has the luxury of peaking late, and I think he will certainly finish in the top three.” In the final sprint, Santorum and his campaign advisers are cognizant of their new place near the top of the Iowa race, but in background conversations, many of his aides say they are wary of making predictions. Instead, they are focusing on turnout — corralling the campaign’s thousand-plus caucus captains, making innumerable phone calls, and tapping online social networks. Ensuring that Santorum’s supporters show up — and bring along friends — is crucial, many say. Sustaining Santorum’s position, especially against better-financed rivals, will be about organization as much as fervor.

Kim Lehman, a longtime pro-life activist and Iowa’s Republican National Committee member, says the campaign’s ability to network among social conservatives will serve it well on Tuesday, even though it operates on a shoestring budget. “He’s gone to 99 counties and met with people, and really given them a chance to get to know him,” she says. “The one thing I keep hearing is that he’s the most accessible, and that he doesn’t give us lip service.” Santorum’s dedication to the ground game, she says, will lead many voters who have met him or heard him speak to caucus for him, even if they have not been officially tabulated ahead of time by the campaign. That’s part of what makes Iowa different, Lehman says, and personal interactions, public discussions of faith, and earnest campaigning can push a second-tier candidate into contention.

“He’s almost like a sleeping giant,” says Lori Jungling, a Santorum aide and Huckabee’s former Iowa adviser. On Sunday night, as Santorum campaigned in western Iowa, she was in Polk County, in central Iowa, coordinating voters in the more populous Des Moines region. Last cycle, Jungling helped Huckabee win Polk County, where over 22,000 Republicans participated in the caucuses, by far the largest turnout for a single county in the state. Winning there supplemented Huckabee’s western tally, and landed a devastating blow to Romney, who needed to win the more urban counties.

This year, Jungling sees a similar opening for Santorum in Polk County, and is applying the lessons she learned from Huckabee’s upstart effort. In other words, sweep the west, and do the same in the rural villages of central Iowa that share western Iowa’s flinty, conservative politics. “The reason Huckabee won Polk County is that he swept the eastern part of the county, which is more conservative,” she says. “Eastern Polk County has many rural communities, and if they come together, they can wipe out whatever happens” near the capital.

It’s no surprise, Jungling adds, that on Monday, Santorum will spend the entire day in central Iowa, campaigning in Polk City, Boone, and Altoona. Bridging his western base with newcomers in the region, many of whom are suddenly recognizing his electability and polling strength, will be the key to an impressive showing, she says.

Santorum, speaking on NBC’s Meet the Press on Sunday, was confident that he would be able to do that, and touted his rapid ascent. “I said my surge is going to come on January 3, after the people of Iowa do what they do, which is actually analyzing the candidates,” he said. “I’ve always realized that when the crunch time comes, in these last two weeks, that’s when we were going to start to pick up, and that’s exactly what happened.”

But later in the day, speaking in Orange City, it was clear that he is taking nothing for granted. He implored supporters to e-mail and call their neighbors. “You here in Iowa are the Lexington and Concord,” he said. “You are the ones who [can] fire the first shot. Do not miss.”

— Robert Costa is a political reporter for National Review.