Noting the porch light left on as he approaches, Vineyarder for Obama Chris Fried chipperly predicts, “These people left early this morning.” He knocks on the door anyway and waits. No answer. He wedges some Democratic leaflets into a crack in the door — the law prohibits him from using the mailbox — and troops back to the car.

It’s Saturday afternoon in Hampton, N. H., and no one is home.

Mr. Fried and fellow Democrats Deborah Medders and Carol Early caught an early ferry to canvas for Sen. Barack Obama in this swing state, where the national political debate has raged for more than a year. Crossing into New Hampshire on I-95, the political landscape becomes decidedly more aggressive than on this polite and liberal Island.

“Live Free Or Die,” declare license plates with the state’s motto.

“Gut Deer?” a bumper sticker asks, in the same font as the famous Got Milk? campaign.

“Obama,” offers a black GMC Yukon.

“NObama,” counters a truck in the other lane.

And in the seaside town of Hampton, some of the streets resemble the parking lot of a polling place on election day for the number of signs supporting one or more candidates.

Ms. Medders pulls up at a green light, so accustomed she is to driving on an Island where anything that blinks means stop. In front, towering over a litter of standard sized signs, a 70-inch placard lists the names of Republican candidates as they will appear on the ballot on Nov. 4.

Back at the Hampton headquarters of the Democratic party on High street, Mr. Fried and his Vineyard colleagues had been prepped for a hard slog by Alexander Boutelle, a 26-year-old volunteer who quit his job as investment banker at Goldman Sachs in early summer to campaign for Obama.

“It’s a game of inches,” Mr. Boutelle coached the volunteers cradling their windbreakers, trenchcoats and clipboards. “There are few touchdowns with immediate conversions.”

When they do encounter life inside the houses on their list of undecided or unidentified voters, the encounters are often brief and unfulfilling. For the canvasser, a door-knocking exchange may be about closing in on support for their candidate, but for the owner, more often than not it is simply about closing the door.

“Canvassers? Oh, fan tas tic,” says one sarcastic respondent.

“I’m for Obama, don’t waste your time,” clips another.

Mr. Fried’s job today is just to identify Democratic voters who can be encouraged to vote on election day, not to change voters’ minds.

But this is surprisingly difficult information to obtain.

“No thank you, I’m pretty well-informed,” says one respondent.

“Political stuff? I can’t tell you that,” says another.

This reluctance is particularly evident — and understandable — in Hampton, where residents in this swing state have been subjected to the election cycle longer and more intensely than most. “New Hampshire people fully know the score,” said Mr. Boutelle. “I’ve literally had someone say ‘Obama, Sununu, and Undecided,’ and close the door.”

While the Vineyarders for Obama divvy up their list outside a block of apartments, Mr. Fried leans over to the driver’s seat and turns off the engine. Environmental protection is one of Mr. Fried’s main concerns as a voter and a citizen.

“I do a sort of cost-benefit analysis for any particular thing that comes into my head to do,” he says.

Today’s activity has run up a significant deficit.

“We’ve burned how many gallons of gas, to knock on doors that were empty? It’s a hefty carbon footprint we’re making.”

Ms. Early volunteers for the Vineyard committee on hunger, and the League of Women Voters.

Ms. Medders has knocked on doors for local elections in South Texas, where she was born and raised, and again when she ran for Tisbury town moderator.

Mr. Fried made some phone calls for the Kerry campaign in 2004.

But all three were stirred by their candidate and by current events to do something more significant in this national election.

Mr. Boutelle said this fact will likely be the strongest selling point on the beat.

“Just say why you’re giving up your Saturday. It’s stronger than 12 negative ads,” he said.

In all, the Vineyarders for Obama knocked on 56 doors. More than half were not answered. But they identified dozens of voters, fielded requests for yard signs, and were thanked for their efforts.

“You came from Martha’s Vineyard today?” asks Phoebe Bischoff, standing in the yard with her husband. “Well, thank you for the work you’re doing.”

The campaign room is still bustling when the group checks back in with their results. Campaign managers pass through collecting signs. A small phone bank is busy at a line of desks along one wall. Boxes of Dunkin Donuts coffee sit almost empty at the front desk, and a small broiler for free hot dogs has been taken in from the street.

Mr. Boutelle is upbeat.

“We’re nose to the grindstone here,” he says. “If 100 people get out to vote because I’ve been here [it’s worth it].”

Back in the car, Ms. Early is knitting the arm for a suit jacket and reflects that she is happy she came though she probably won’t be coming back next week for the get-out-the-vote push.

“I just wanted to do something for Obama,” she says.