"It's the Electoral College now that's in play, and Maryland is sandwiched between two states that can probably make a difference," he said.

Brandon, a ninth-grader at West Nottingham Academy, is a veteran GOP campaigner already, having volunteered on behalf of former Gov. Robert L. Ehrlich Jr., Rep. Andy Harris and 2008 presidential nominee John McCain. The bus trip to Havertown was his first taste of cross-border campaigning, but he knew exactly why he was going.

"We know Maryland's not going to go Republican because it's just a solid blue state," he said. But with Pennsylvania and Virginia, he figures, Romney can get to the needed 270 electoral votes.

"Not many 14-year-olds like this kind of stuff, but it's something that's addictive," he said.

Once in Havertown, the Marylanders split up and headed to neighborhoods assigned by the local Republican Victory Committee.

Craig and his son Randy, a Havre de Grace town commissioner, teamed up to go door-to-door in a middle-class neighborhood that has been trending Democratic in recent years. Armed with a list of voters local Republicans had identified as undecided, they knocked on doors polling voters on their intentions.

As veteran campaigners, the Craigs were not surprised to find Not at Home leading by landslide proportions. But they were pleased to find Romney well ahead among voters who had made up their minds.

David Eberlin, a local resident, pulled up in his minivan to chat with the visiting Marylanders. He told them the neighborhood had been awash with Obama signs in 2008 but that now few could be seen.

At the more than 30 homes they visited before breaking for lunch, the Craigs didn't meet any voters who seemed inclined to listen to a sales pitch. Nor did the Craigs apply any pressure. Mostly they concentrated on observing a rule David Craig said he has been teaching for years: "You never walk on their grass."

Making a difference

Though volunteers often get some coaching before they hit the field, there is still mystery involved in knocking on a stranger's door. They never know just what they're going to get. For Jeff Biggs, a 47-year-old technology consultant from Columbia who's working for Obama, that took some getting used to. Now, he says, he appreciates the exchanges, even when he comes across a Romney supporter.

"It can be a little bit intimidating at first — for me, even just phone banking was initially outside of my comfort area," said Biggs, who had not previously volunteered on a campaign but has been canvassing for the president every weekend since the spring. "I think what we need in our country is to have people who have different ideas at least to be comfortable talking to each other."

Earlier this year Biggs encountered a Virginia voter who had lost faith in Obama since 2008. The two had a long discussion in which Biggs explained why Obama's controversial health care law was important to him personally. That conversation spilled into a friendly email exchange that lasted for several weeks.

Biggs thinks he probably brought the voter back in the fold for Obama. Even if he didn't, the interaction was likely more effective than any 30-second television ad.