(CBS News) MANCHESTER, N.H. -- Almost three months after his resounding victory in the New Hampshire primary launched Mitt Romney toward the Republican nomination, his former campaign headquarters here is empty.
A "for lease" sign is plastered across the window of the inconspicuous storefront on Elm Street, and there are no indications that the staff and resources devoted to Romney's strongest early primary win are close to getting back to work in what is shaping up as an important swing state in the general election.
About a half-mile down the road on Maple Street is another campaign office that has been bustling with activity since it opened in October. Inside, young staffers from around the country and local volunteers are taking advantage of abundant resources to lay the groundwork for President Obama's push to win New Hampshire's four electoral votes in November.
Jez Taft, a 33-year-old volunteer from Manchester who also works part time at a local kennel, spent Wednesday morning on data-entry duty. Taft was an Obama volunteer during the 2008 campaign, and although she said the pace of the current campaign is calm, she is in no way tempted to slack off.
"The people I talk to personally are just as passionate as they were the last time, but I hear a lot of complacency, too," she said. "People think it's going to be easy. And for me personally, that's terrifying."
As a small but electorally significant state that is expected to be up for grabs in November, New Hampshire is a microcosm of the massive organizational head start that Obama's re-election team enjoys over the Romney campaign, which is still working to wrap up the GOP nomination for the former Massachusetts governor.
The Obama team already has more than 30 paid staffers on the ground in New Hampshire and is expanding rapidly across the state. Its headquarters in Manchester is one of seven Obama field offices here, and the president's campaign has already held several events in each of the state's 10 counties.
By contrast, Romney does not have any paid staffers on the ground, and his campaign has barely maintained a footprint in the state.
Long enmeshed in a combative primary fight, the Romney campaign is only now shifting into serious preparations for taking on what is widely expected to be the most formidable ground game in the history of American politics.
Romney does retain some clear advantages in New Hampshire, but they are based largely on his background as the summertime resident of a home on Lake Winnipesaukee and as a familiar face from a neighboring state who has campaigned extensively here for the past five years.
"We're going to be the underdog here," said Jim Merrill, who was Romney's senior New Hampshire adviser during the 2012 primary campaign. "We understand the president has a head start and he has that benefit as an incumbent, but we're not going to cede an inch to him."
Like other key former staffers here, Merrill travelled extensively to work elsewhere after the New Hampshire primary, serving stints in Florida, Michigan, Vermont and Maine. He has returned to his home in the state, where he serves as a political consultant for gubernatorial candidate Ovide Lamontagne. Merrill said he is awaiting marching orders from Romney headquarters in Boston while he quietly networks among the state's political community and plots how he might reset the groundwork for a campaign operation that is, in his words, "waiting to be reactivated."
Some Republicans have sought to downplay the value of building an early ground game for a general election in which hundreds of millions of dollars will be spent on mass media.
The Romney team plans to outsource many organizational duties to the Republican National Committee, and Romney's political director, Rich Beeson, recently told the Los Angeles Times that he "wasn't losing sleep" over his campaign's ability to compete on the ground in November.
But Merrill, who helped steer George W. Bush to victory over Al Gore in New Hampshire 12 years ago -- which proved essential to Bush winning the presidency -- has had a front-row view of the massive Obama infrastructure locally. He emphasized the extent to which Romney will be playing catch-up this spring and summer.
"In New Hampshire, it's sweat equity, and you get what you put into it," Merrill said. "If Mitt's the nominee, we've got work to do up here. New Hampshire is a place that I think is absolutely in play, but they're working hard up here. The president has clearly made New Hampshire a focal point based on the level of attention they've been giving it the last few months."
Despite the state's modest delegate haul, the Obama campaign has indeed invested significant time and resources here, indicating that they see it as a vital part of the president's path to 270 electoral votes. Obama has visited the state twice since November, and Vice President Biden is slated to make his third trip of 2012 to the state next Thursday.
"The path to the White House runs right through New Hampshire," said Obama's New Hampshire communications director, Holly Shulman. "From Pelham to Pittsburg and Hampton to Hanover, we are reaching out to voters and talking about the president's message and the stark contrast between him and the Republican candidates in this race."
At the Obama field office in Nashua on Wednesday, volunteers filed in and out of the building, picking up and dropping off campaign-issued cell phonesthat were piled on a table in the back of the room.
"There's so much misinformation about health care reform out there," a volunteer explained to one voter over the phone. "People don't understand the benefits of it."
Seated in front of a wall that was decked in campaign signs and instructions for volunteers with titles like "Canvas 101," Mike Pederson of Nashua reviewed the talking points that had been handed to him by the campaign. The focus of the phone-banking operation on this day was on how the health care reform law would affect Medicare, and he stayed on message as he ignored the full spread of Girl Scout cookies, soft drinks and vegetables that had been set up on a nearby table.
Pederson raved about the energy he witnessed at a recent "Latino night" that the campaign had held at the local VFW hall, and he didn't seem fazed when one of his target voters hung up on him rather than listen to his pitch.
"Some people don't want to talk at all, and others are very receptive," Pederson said. "I do not want to wake up the day after the election and find out we lost because we didn't give it our best shot."
All of the volunteers who worked the morning shift in Nashua said that they plan to keep donating their time right up until Election Day.
And just in case any of them were tempted to let up, a sign on the door on the way out of office was a stark reminder of the ominous "for lease" advertisement that adorned the old Romney headquarters.
"Did you sign up to come again?" the homemade Obama campaign poster asked the volunteers. "We'd love to see you!"