John F. Kerry told community leaders here Tuesday that he strongly opposes burying nuclear waste at Yucca Mountain, providing a contrast to President Bush on one of the dominant political issues in this crucial state.

The Democratic presidential nominee said Bush is threatening the security and economic vitality of Nevadans with his plan to ship spent nuclear waste from around the country for storage in the mountain 90 miles northwest of here.

Kerry said that if he is elected, he will cancel the project, which already has cost the federal government billions and eventually could cost as much as $60 billion.

"Yucca Mountain to me is a symbol of the recklessness and the arrogance for which they are willing to proceed with respect to the safety issues and concerns of the American people," Kerry said on the 12th day of his post-convention, coast-to-coast swing through battleground country. "When John Kerry is president, there will be no nuclear waste at Yucca."

In the 2000 campaign, Bush said he would oppose the Yucca Mountain site unless it was deemed scientifically safe, a position state political analysts credited for helping the Republican narrowly carry Nevada. One year after taking office, however, Bush designated the mountain the final -- and environmentally safe -- resting place for the dangerous nuclear waste currently stored at more than 100 other locations around the country.

Sen. Harry Reid (D-Nev.) told reporters here Bush "lied" in 2000 and would pay the price of losing Nevada this fall. "The state of Nevada is going down the drain" for the GOP, he said.

Republican strategists privately concede this issue alone could cost Bush the state's five electoral votes in a close race. In a blow to Bush, Sen. John Ensign (R-Nev.), recently said Kerry would be better for the state on this pivotal issue. Matthew Dowd, a top Bush strategist, said the president will not lose the state over Yucca because his polls show voters here are more concerned about terrorism and the economy.

Politically speaking, Yucca Mountain is to Nevada what corn is to Iowa or oil to Texas. It is a rare issue that unites Democrats and Republicans alike and can turn an election. Bill Clinton became an enthusiastic opponent of the Yucca site and carried the state in 1992 and 1996.

Kerry is hoping for the same result this year. While Kerry voted in 1987 to consider Yucca Mountain as the exclusive storage site, he has generally opposed it on environmental and safety grounds over the past decade.

Kerry's running mate, Sen. John Edwards (N.C.), has supported a nuclear repository at Yucca Mountain during his one term in office but now opposes it. Reid said Edwards called him the night before Edwards was named the Democratic vice presidential candidate and told him "I am on the Yucca Mountain bandwagon."

"Nevadans should not be fooled by election-year pandering," Ensign said in a statement.

Outside of the state, the larger issue of what to do with the nation's highly radioactive nuclear waste from fuel rods and other sources has vexed federal policymakers for more than two decades. Most lawmakers want a single site to store tens of thousands of metric tons of nuclear waste deep below the earth's surface, where it will never contaminate land or water. But nobody wants nuclear material buried in their back yard, and nobody can give a guarantee that it will not eventually seep into the groundwater or rise to the surface many years down the road. Bush and supporters of the Yucca plan say studies prove its a safe and wise idea.

Further complicating matters is how to transport such dangerous materials, in some cases, across the country. An accident -- or terrorist attack -- on a vehicle transporting nuclear waste could prove disastrous. Since the Sept. 11, 2001, terrorist attacks, opponents of the Yucca Mountain plan have increasingly pointed to this potential for terrorism to support their case that the waste should stay in its current resting places.

"The bottom line here is to make America safe," Kerry said. "In an age of terror we need to make sure the movement [of the material] . . . is able to be guarded" from attack.

If elected, Kerry would "establish an international, independent, blue-ribbon panel to recommend world class, state of the art scientific methods for nuclear waste storage," according to a campaign policy paper. Only then, he said, would a Kerry administration determine where the waste would be stored -- but it will not be at Yucca.