(FORTUNE Small Business) – After the Catholic church, AAA--the official name of the American Automobile Association--is the second-largest organization in the U.S. With 46 million members, the century-old AAA is a beloved American institution. Beloved by everyone, that is, but environmentalists.

Critics claim that AAA's membership dues help pay for lobbyists who promote an anti-environmental agenda. "They oppose efforts to improve the fuel economy of vehicles, cut down pollution from vehicles, fund public transportation, and limit sprawl," says Daniel Becker, director of the Sierra Club's Global Warming and Energy program. AAA flatly denies the charges, but its record is hard to ignore. In 1990 AAA publicly opposed the strengthening of the Clean Air Act.

Last June two Portland, Ore., entrepreneurs, Mitch Rofsky and Todd Silberman, created the Better World Club. On the surface it doesn't look too different from AAA, offering the same services and using the same tow trucks, for pretty much the same price. But instead of using some resources for lobbying, it donates them to organizations that remove the carbon-dioxide emissions that travel creates.

Rofsky and Silberman met in the Cub Scouts 40 years ago. Rofsky became an initial backer and later president of Working Assets, a socially responsible mutual fund that created a successful long-distance telephone company. Silberman founded Lifeco, a $1.4 billion travel agency he sold to American Express in 1990.

It won't be easy for a startup to challenge AAA--Better World Club aims to be 1% as big someday. (Rofsky is hoping to drum up investors to fund the company's first major marketing push.) And there is a chance, however slim, that the Better World Club may be a victim of its own success--some observers say that AAA has recently downplayed its lobbying efforts. "We're pleased to be here to inspire them to moderate their tone," Rofsky says. "But it's not about tone. It's about action."