Opponents of a nuclear waste dump in the Nevada desert are taking their fight to the airwaves — in Vermont.

An ad, which began airing Tuesday and will run for a couple of weeks, asks viewers to call Vermont's senators, who will vote on the Yucca Mountain project this summer.

Organizers chose Vermont as the first state to air the commercial because it has a strong environmental movement that often works closely with the state's political leaders. And one of Vermont's senators, independent James Jeffords, chairs the Senate's environment con choosing Vermont, however, opponents also underscored the difficulty of their task. Jeffords, Democratic Sen. Patrick Leahy and Democratic Gov. Howard Dean all support the Nevada dump.

A prime reason for their backing lies in the cooling pools at the Vermont Yankee nuclear plant in Vernon, Vt., where spent nuclear fuel has accumulated for 30 years.

"The alternative to Yucca Mountain would be to store spent nuclear fuel in 'dry casks' on the banks of the Connecticut River, which I believe poses serious and unacceptable environmental and safety risks," Jeffords said in a statement. Dry casks are giant concrete and steel containers; most spent nuclear fuel is kept in water to cool it.

Leahy spokesman David Carle said the senator still favors Yucca Mountain but wants the Bush administration to answer questions raised about transporting the waste around the country.

A major thrust of the opposition is that shipping the waste from the nation's nuclear plants through more than four dozen states to Nevada runs a risk of accidents, with the potential for radioactive releases.

The shipments by truck, train and, possibly, barge also could be targets for terrorists, opponents say.

"If we license Yucca Mountain, every day can be Sept. 11 because that is the kind of threat we're exposing our nation, our communities, our families to," said Carl Pope, president of the Sierra Club, at an anti-Yucca Mountain rally Tuesday at the foot of the Capitol.

The radio commercial stresses the potential for accidents and contends approval of Yucca Mountain would lead to "dozens of new nuclear power plants."

"That's the goal of the nuclear power industry," the announcer says in the 30-second ad, paid for by environmental groups. Opponents are considering more ads but will not say where they will run.

Environmental activists and members of Congress who oppose Yucca Mountain are recommending the same type of onsite storage that Jeffords criticized.

The Senate vote this summer is expected to be the last legislative chance to kill plans for the repository for 77,000 tons of radioactive waste beneath a volcanic ridge 90 miles northwest of Las Vegas.

Nevada Gov. Kenny Guinn, under unusual rules written by Congress, rejected President Bush's recommendation of the site this month. Congress will cast the deciding vote.

Sen. Harry Reid, D-Nev., admitted to the Capitol demonstrators that opponents lack the votes to kill the project. He said, however, that several senators remain undecided.

The House is expected to ratify Bush's recommendation. A vote is likely in late April or early May, Rep. Joe Barton, R-Texas, said Tuesday at a news conference organized by Yucca Mountain supporters.

"We're now coming at least to the beginning of the end," Barton said, referring to the 20 years and $7 billion the federal government has spent studying the issue.