In the last presidential election, Paul Shea, 35, did not vote, assuming it was unimportant. But now he is walking the city's streets, trying to convince like-minded environmentalists that they cannot afford to let President Bush win reelection.

"He has eroded away at all the laws," said Shea, a business management student at nearby Drexel University. "I don't understand where somebody has to live on Earth, where they don't care about poisoning the planet."

Shea is the face of what Sierra Club officials like to call the "infrequent environmental voter," someone who cares about wildlife habitat and air quality but may not make it to the polls regularly. He is on the front lines of their efforts to reach nearly 500,000 Americans before Election Day, spreading the message that Democrat John F. Kerry will protect the environment better than the incumbent.

While environmental organizations have not delivered as much as they promised in past elections, they say this year will be different. In a closely divided election, these groups are focused on swaying voters in swing states that will help decide this year's race.

Sierra Club political director Greg Haegele acknowledges that most voters "generally are not moved by the environment when making their decision about the president." But those who are, he said, will hear from club members as many as eight to 12 times before November. "Our job is to go find them and turn them out," Haegele said. "The environmental movement is now learning how it can translate its base support into electoral power."

The Sierra Club, like many politically active groups this year, has a sophisticated ground operation. Gone are the days when activists plowed through neighborhoods one house at a time. Instead, the Sierra Club has selected each home its activists will visit, based on voting records, polling data and club membership rosters. It is a more precise way to reach voters, and it ensures a higher likelihood of success.

This new approach reflects, in part, how changing campaign finance law has shifted outside groups' strategies. In past years the Sierra Club has poured millions of dollars into television ads: This election, nearly all of its $10 million campaign fund will go into direct voter contact, through canvassing, phone calls and e-mails. The group is targeting Florida, Minnesota, Nevada, New Hampshire, New Mexico, Ohio, Pennsylvania and Wisconsin.

The League of Conservation Voters, another environmental heavy hitter that came out early for Kerry in the Democratic primaries, is spending $6 million, its largest campaign budget in history. Its resources, which are pouring into the swing states of Florida, New Mexico, Oregon, Pennsylvania and Wisconsin, are largely aimed at reaching half a million households in those states three different times.

"Having a personal conversation is much more persuasive and much more compelling to voters," said the group's political director, Mark Longabaugh, a campaign veteran who ran for Congress in 1996 against Rep. Steve Chabot (R-Ohio).

Both groups are relying on environmentalists from less critical states to bolster their ranks in key states. The Sierra Club has a "Road to Somewhere" program in which members from California take buses to Nevada, a competitive state. When Longabaugh visited more than a dozen student canvassers in Oregon, he discovered that not one hailed from the state.

Bush campaign spokesman Terry Holt calls these activists "special interest lobbyists who have made partisanship a first priority" and says, "The president's policies on the environment are unparalleled."

Susan Gobreski, Pennsylvania director of the League of Conservation Voters, chafes at the special interest label, saying she is helping voters make the connection between Bush's environmental policies and who they want in office. "There's information out there that might affect how they want to vote in this election," she said.

Such information includes the president's support of drilling in Alaska's Arctic National Wildlife Refuge while Kerry led the Senate opposition to the project, and Kerry's advocacy of controls for international greenhouse gas emissions as part of the Kyoto treaty, which Bush rejected shortly after taking office. Kerry has a 92 percent favorable lifetime voting record in the eyes of the league, while Bush is the only president in its history to receive an F.

Bush campaign chairman Marc Racicot said the president will defend himself against environmental attacks: "We believe we have a good story to tell the American people."

But activists such as David Chermol are telling a different story. Chermol, a 33-year-old lawyer for the Social Security Administration, took an afternoon off work last week to knock on doors in Montgomery County, a key swing suburb just outside Philadelphia.

Chermol has not canvassed in 10 years, but he displays the skills of a master. While he has a standard script (he begins by asking residents whether the country is headed in the right direction and then contrasts the two candidates' environmental records), he adjusts his message depending on the voter.

When David Tabb, 24, tells Chermol he is unemployed, Chermol replies, "That's as good a reason as any to vote for John Kerry, right?" Rose Kozak, 26, says she is wavering and wants to judge the two men on their support for same-sex marriage and stem cell research; Chermol tells her Kerry is the one who backs her positions.

He even takes the time to compliment nurse Barbara Pacca on the rose detailing on her entryway ceiling. "I did that," she says, smiling.

Mark Longabaugh is the League of Conservation Voters' political chief.