MIDDLEBURY, Vt. — Leaders of the environmental movement were livid last fall when Michael Shellenberger and Ted Nordhaus, two little-known, itinerant environmentalists in their 30s, presented a 12,000-word thesis arguing that environmentalism was dead.

It did not help that the pair first distributed their paper, "The Death of Environmentalism," at the annual meeting of deep-pocketed foundation executives who underwrite the environmental establishment. But few outsiders paid much attention at first.

Then came the November elections, into which groups such as the Sierra Club and the League of Conservation Voters poured at least $15 million, much of it to defeat President Bush, whose support for oil drilling and logging and opposition to regulating greenhouse gases have made him anathema to environmental groups. Instead, Bush and congressional champions of his agenda cemented their control in Washington at a time when battles loom over clean air and oil drilling in the Arctic National Wildlife Refuge.

A debate about the future of environmentalism now is ricocheting across the Internet about the authors' notion of, in Shellenberger's words, "abolishing the category" of environmentalism and embracing a wider spectrum of liberal issues to "release the power of progressivism."

Carl Pope, executive director of the Sierra Club, began things in the fall with a bristling, 6,000-word denunciation of Shellenberger and Nordhaus' paper. An online magazine, Grist.org, has started a forum to debate their ideas and their assertions that environmentalism has become "just another special interest."

One writer called the paper "ridiculous and self-serving." Another wrote simply, "I'm not dead."

Others have embraced the paper.

Nordhaus, 38, is a pollster, and Shellenberger, 33, is a strategist and the executive director of the Breakthrough Institute, a new organization that advocates putting progressive values to work to solve problems. They are receiving an increasing number of speaking invitations such as the one that brought them to Middlebury College in central Vermont recently, where they spoke at a conference on rethinking the politics of climate.

The election results may not have been the only reason they have struck a nerve. Other nagging concerns abound, such as worries about the effect of repeated defeats on morale and concerns about image; a recent survey conducted for the Nature Conservancy suggested that the group use the term "conservationist" rather than "environmentalist."

"To a large extent, most of us in the environmental movement think most people agree with us," said Bill McKibben, a scholar in residence at Middlebury College and the author of "The End of Nature," a 1989 book on global warming.

But McKibben, who called Shellenberger and Nordhaus "the bad boys of American environmentalism," said their data showed that the kind of political support the movement had in the late 1970s was gone. "The political ecosystem is as real as the physical ecosystem so we might as well deal with it," he said.

Their paper asserts that the movement's senior leadership was blinded by its early successes and has become short-sighted and "just another special interest." Its gloomy warnings and geeky, technocentric policy prescriptions are profoundly out of step with the electorate, Shellenberger and Nordhaus say.

"We have become convinced that modern environmentalism, with all of its unexamined assumptions, outdated concepts and exhausted strategies, must die so that something new can live," they wrote. As proof, they cite the debate on global warming and the largely unsuccessful push for federal regulation of industrial and automobile emissions.

They chided the movement for its limited efforts to find common ground with other groups, such as labor, and urged their compatriots to tap into the country's optimism.

The authors' arguments are based partly on data from a Canadian polling company, Environics, which show U.S. voters edging away from the environmentalists and some of their allies. For example, the percentage of the 2,500 people in the poll who agree that pollution is necessary to preserve jobs increased from 17 percent in 1992 to 29 percent in 2004.

The paper — based largely on interviews with 25 environmental leaders — has exposed latent fault lines among groups who battle for strategies to preserve wetlands, save endangered species and the wilderness, and eliminate toxic pollutants in the air and water.

The observations have rippled through the environmental movement to the anger of some of its leaders and foundation executives and to the applause of a scattering of younger or less-visible activists.

John Passacantando, executive director of Greenpeace USA, was the only national environmental leader in Vermont to hear the pair at the conference. "These guys laid out some fascinating data," Passacantando said, "but they put it in this over-the-top language and did it in this in-your-face way."

The movement always has counted on overwhelming expressions of support; polls consistently show approval of 70 to 80 percent or more. Memberships have been rising steadily at organizations such as the Sierra Club, which reported an increase in membership from about 642,000 in 2000 to 750,000 last year. That helps those who dismiss Shellenberger and Nordhaus as upstarts.

"The environmental movement is probably the strongest social movement we have in this country," said Joshua Reichert, director of the environment division of the Pew Charitable Trusts, a major source of financing for environmental causes. "It reflects the values and aspirations of a huge majority of the country — but it simply can't compete with war and terrorism, nor should we expect it to."

Deb Callahan, president of the League of Conservation Voters, said the movement had been changing even before the paper was written. "I think what we are looking at is the rebirth of environmentalism, examining constituencies, messages and focus and going beyond what we've been comfortable with," Callahan said. But she agreed that success was not at hand as she and her colleagues confront "the most hostile federal government we've seen in the history of the environmental movement," she said.

The decision by Shellenberger and Nordhaus to pick global warming as Exhibit A of their argument, Pope said, was unfair. "Since global warming is our hardest problem, and we brought to bear our weakest tool, expertise, it's hardly surprising that we are getting our worst results," he said.

Pope also took a dig at his adversaries' motives. "Given that the chosen audience of the paper was the funders," he wrote, "it will be hard for many readers to avoid the suspicion that the not-so-hidden message was, 'Fund us instead.' "

In the trenches, the reviews were more positive. In San Francisco last year, Adam Werbach, who in his early 20s was the national president of the Sierra Club, joined the chorus with a speech that echoed the tone of the Shellenberger-Nordhaus paper.

And in an e-mail to Pope, Gerald Winegrad, a Sierra Club member and a board member of the Maryland League of Conservation voters, wrote, "We are failing now, I would suggest very badly, in accomplishing our goals."