WASHINGTON — For environmentalists hoping to turn anger at President Bush into electoral votes for John Kerry, the biggest and perhaps only field of dreams is a nuclear waste dump site in Nevada.

Lesser hopes are pinned on mercury-polluted waterways in Wisconsin and Florida and woodlands threatened by road-building and other development in Arizona, New Mexico, and Oregon. Voters upset at Bush's environmental record might give Kerry a boost in all those states.

But Nevada, where Bush wants to entomb a half-century's waste from atomic power plants, is the only state where an environmental issue can realistically swing the outcome, according to environmental leaders and political analysts.

"Kerry is competitive because of it," said Ted Jelen, chair of political science at the University of Nevada at Las Vegas. "He otherwise wouldn't have much of a chance."

Environmental groups are mostly staying away from Nevada, aware their unpopularity in the state might hurt Kerry, a Massachusetts senator.

Bush won Nevada, 50-46 percent, over Democrat Al Gore in 2000. But the state is fighting the Bush administration over building a nuclear waste dump in the desert 90 miles from Las Vegas.

Kerry has consistently voted against Nevada's Yucca Mountain as the site for the waste repository from the time Congress picked it in 1987.

Jelen said there is a widespread perception that Bush lied about basing his decision on science, and Democrats profited with heavy turnout at caucuses in February. Yet environmental causes remain "an unpopular symbol" in a state heavy with ranching and mining interests.

"Kerry's position is simple: 'Bush lied to you; I will reverse it,'" Jelen said. "The Republicans and the Bush campaign have not come up with a good response to that."

The Bush and Kerry campaigns declined to comment. On Sunday, the Las Vegas Review-Journal, Nevada's largest newspaper, endorsed Bush for re-election in an editorial that applauded his response to the Sept. 11 terrorist attacks and called him "the right president at the right time."

Questions remain over the $58 billion Yucca project. The movement of water through rocks might corrode waste canisters. In February, Bush said 20 years and nearly $7 billion worth of study had convinced him the project was scientifically sound.

More broadly, Republicans do not see the environment as a bright spot for Bush. Jim DiPeso, policy director for REP America, a pro-Republican environmental group based in Albuquerque, New Mexico, pointed only to Bush's new goals for increasing wetlands and rules to reduce diesel pollution.

"There isn't much that he has to run on to turn out environmental voters for him," DiPeso said. "It's not their strength; they know it's not their strength."

He said Kerry could benefit in Western states like New Mexico and Arizona, where ranchers, hunters, fishers, and environmentalists all worry about oil and gas drilling on public lands and logging in national forests.

Likewise, in Nevada. "If enough votes are guided by concern about Yucca Mountain ... it's very conceivable those five electoral votes could end up in Kerry's column," DiPeso said.

The League of Conservation Voters, which considers itself the political arm of the environmental movement, is spending $6 million to defeat Bush. The Sierra Club, the only other major political player among environmental groups, is spending $5 million. Defenders of Wildlife is spending $750,000 in its first such political foray.

The three groups are each going after voters in Florida, New Mexico, Oregon, Pennsylvania, and Wisconsin. All but Pennsylvania had the closest margins in the 2000 presidential race.

The Sierra Club and Defenders of Wildlife also are putting efforts into Nevada and New Hampshire, and the Sierra Club also is working in Minnesota and Ohio. Defenders of Wildlife is in Arizona, Colorado, Maine, and Washington state.

"We may yet move into Nevada," said Mark Longabaugh, senior vice president for political affairs at the League of Conservation Voters. "Partly, it's a resource decision."

Carl Pope, executive director of the Sierra Club, says his group missed recognizing the potential for the race to tighten in Arizona.

Seldom does the environment play more than a background role in determining who occupies the White House. But Pope see worries about air and water pollution fitting with broader security concerns this election.

"It's about family safety this year," Pope said. "This election is about turnout."

Rodger Schlickeisen, president of Defenders of Wildlife, described Bush and Kerry as polar opposites on reducing air and water pollution and protecting and using natural resources.

"We think if it's as close as it was in 2000, we can make the difference in three or four states," he said.