espite this enthusiasm, REP remains a small group. Its rank-and-file members are scattered around the country, so they don't constitute a critical mass of voters in any one district. According to Patrick Michaels, a senior fellow with the libertarian Cato Institute, "REP doesn't have a high profile in Republican circles."

I ask Marks how REP has made a difference in Congress, and she describes meeting with Senator John McCain in the Phoenix airport a week after the 2000 New Hampshire primary. Voters along the campaign trail had been asking for his position on global warming. "He asked me, 'What should I tell them?' I gulped. He needed to hear it from us, because we're a Republican group." Within a week DiPeso had pulled together a paper from which McCain was soon quoting.

There are signs that REP's influence is growing, says Betsy Loyless, vice president of policy for the League of Conservation Voters. "Part of Martha's value is the people she can reach, the moderate Republican members of Congress and voters." A number of these moderates sit on REP's honorary board, including Senators McCain (Arizona), Susan Collins (Maine), and Lincoln Chaffee (Rhode Island) and Representatives Mark Kirk (Illinois), Christopher Shays (Connecticut), and Sherwood Boehlert (New York).

The more entrenched Washington power brokers are a much tougher audience, however, and one Marks has little hope of influencing. "We're not changing Tom DeLay or Richard Pombo into environmentally minded people," says Marks. "Neither grew up with a conservation ethic. Pombo [chair of the House Resources Committee] is a rancher who came to government vowing to destroy the Endangered Species Act, and DeLay is a former exterminator."