The trouble began with yard signs.

Rick Santorum’s campaign had ordered 4,000 for South Carolina back in December, which to the realists on his staff had seemed like way too many, because the Republican presidential candidate was drawing 1 percent support in local polls and a crowd of 11 people to the Waffle House by offering to buy their breakfasts. But then Santorum finished deadlocked for first place with Mitt Romney in the Jan. 3 Iowa caucuses, and a surge of donations shut down his Web site. The 4,000 signs were snatched up within hours.

Now it was six sleepless days later, and Kerry Wood, Santorum’s top adviser in South Carolina, jammed his cowboy boot hard on the accelerator of a rental car, pushing it to 85 miles per hour through tobacco country, racing to keep pace with the momentum he’d worked so hard to create. Even after an uninspiring fourth-place finish in the New Hampshire primary, Santorum was continuing to enjoy newfound popularity in conservative South Carolina, where crowds of 300 gathered at his rallies to chant “We Pick Rick!” Those supporters also wanted bumper stickers, signs and instructions from the campaign.

“I wish I could find some way to move twice as fast and do twice as much,” Wood said, “or maybe just clone myself.”

The state’s Jan. 21 Republican primary was less than two weeks away. It would be the defining moment of Santorum’s political career, a chance to galvanize tea party support and assert himself as Romney’s main challenger, and Wood wondered whether his small team of volunteers and county chairmen had the infrastructure necessary to meet the moment. They had spent the past year trying to prove that theirs was a major campaign. Now they had little time to become one.

“A campaign with momentum takes on a life of its own,” Wood said. “There’s a lot that wakes me up now at 3 in the morning.”

He needed more yard signs.

He needed offices where he could store those signs.

He needed keys, computers and phones for those offices.

He needed a staff to answers those phones.

He needed buildings that could accommodate gatherings of 300 or more for two dozen Santorum events scheduled before primary day, and a six-person advance team to plan out those events, and bumper stickers to pass out to the supporters, and surrogate speakers to introduce the candidate, and traveling sound technicians, and media handlers, and a plane, and seven sport-utility vehicles for the candidate’s family, and a security crew that would be willing to dress inconspicuously to try to blend into crowds, because Santorum believed that keeping the campaign “lean” was central to his appeal. In fact, the candidate still wanted to travel to most events by himself, which would mean procuring the familiar pickup truck with Iowa plates.

Wood said he had barely slept or eaten in the past week as he tried to keep pace with 250 calls and e-mails that lit up his cellphone from 6 a.m. until midnight. He had watched so many other campaigns collapse under the weight of their own success: Bachmann. Perry. Cain. Gingrich. Even though Santorum had come in fourth in New Hampshire, his focus had always been on South Carolina, where the team planned to spend $1.5 million on advertising.

“This is our moment right now,” Wood said, “so I have to be able to do three or four things at once.”

This trip was taking him from a staff meeting in Charleston to a rally with Santorum in Greenville, a four-hour drive that he hoped to make in three. On the way, he managed to secure a deal for 10,000 yard signs from Herman Cain’s disbanded campaign — “They were just going to throw them in a dumpster,” he said — and a volunteer had been dispatched to Georgia in a U-Haul to pick them up. It was a transaction befitting of a contest that swaps one front-runner for the next: Wood planned to reuse the metal frames but replace the thin plastic signs, subbing “Yes We Cain” for “Rick Santorum for President: Join the Fight.”

The trunk of his rental car also contained 30 desk phones, which had been shipped overnight from Iowa and would be used to set up a phone bank in Greenville. There were bumper stickers in his glove box that he would distribute across five Santorum campaign offices opening in the coming week. In the back seat sat a junior staff member, who right now was talking about the need to hire more junior staff members, because they had only four and cloning was not a possibility as of yet.

“How many people do we have coming to help from Iowa?” the junior staffer asked.

“Hopefully a lot,” Wood said.

“When are they going to get here?”

“I don’t know.”

“Where exactly are they going?”

“I’m still not sure.”

Wood started a career in politics almost a decade earlier, and it has consumed him ever since. He had been a computer programmer who wrote medical software until a friend decided to run for statewide office and asked Wood to analyze some voter data. The friend won his race in an upset, and soon other politicians began calling Wood for advice. He launched his own political strategy group for conservative candidates in 2006 and now supports about five or 10 state and local campaigns each year.

In early November, the South Carolina Republican Party asked him to help run a presidential debate at Wofford College in Spartanburg. He arranged the event details for all of the candidates, making sure that Michele Bachmann’s green room was stocked with pizza and that Herman Cain had hot water with six slices of lemon. Santorum told Wood that he liked Fresca but was happy to eat and drink anything. He seemed “hard-working and down-to-earth,” said Wood, who also liked the candidate’s frank conservatism on social issues. He accepted a job with Santorum a few weeks later.

In the months that followed, Wood had become more emotionally invested than he imagined possible. He considered himself a data guy, a strategist, a “nuts-and-bolts nerd.” At 45, he had the imposing shoulders of a kayaker and a salt-and-pepper goatee, with eyes that tended to narrow in skepticism. But lately, as he watched Santorum’s crowds swell in Iowa, New Hampshire and now South Carolina, he had come to see his work less as a job than as cause. “It feels like being part of a huge movement that just exploded,” he said.

The campaign had the difficult task of keeping pace. Some supporters had started to complain about a lack of organization on a Facebook page for Santorum in South Carolina.

“I have several numbers for Santorum staff, but no one is answering their phone or returning emails,” wrote one.

“The Santorum stickers I have been begging for, for several weeks, aren’t coming,” wrote another.

“No one is minding the store,” wrote a third.

Wood was in the process of addressing their concerns, or hiring people to do so for him. Santorum had raised more than $3 million after doing well in Iowa, and Wood suddenly was gifted with money to rent office space and $15,000 to pay a temporary staff. “It’s nice to be able to afford to do some things, but we are used to operating tight,” he said. He had found volunteers to act as coordinators in 42 of South Carolina’s 46 counties. Media strategists were coming from Virginia. He would offer instructions to the team by phone while accompanying Santorum to at least one event in every county, a repeat of his Iowa strategy, which required five or six appearances each day.

Now Wood pulled his rental car into Greenville for the next Santorum event and checked his watch. Not quite three hours, but only three hours and 15 minutes. “Not bad,” he said. His team had hurried the plan into place for this event over the past three days, settling for a sports bar on the outskirts of town and not issuing a press release. “Sometimes you throw it together and hope it works,” Wood said.

The parking lot was overflowing. About 500 supporters jammed the restaurant. Yard signs covered the lawn. Volunteers handed out Santorum stickers. The candidate pulled up in his truck. Television cameras surrounded him. His microphone worked. The audience chanted “We Pick Rick.”

“That’s momentum,” Santorum told them, caught up in the moment, beaming, and it seemed just as simple as that.