The hearings may well take place. Sen. Barbara Boxer, D-Calif., chairwoman of the Environment and Public Works Committee on which Clinton sits, reportedly agreed to schedule them soon after the Senate reconvenes in September.

Politically, analysts say, Clinton moved adroitly to put herself out front on Nevada's pet issue. More important than her opposition to the nuclear dump was the gesture she made.

"It's smart politics," said University of Nevada, Las Vegas political scientist Kenneth Fernandez. "She's the strong front-runner, but she's not resting on her laurels. The Nevada caucus is quickly approaching, so she's sending a message."

Clinton's message to Nevada Democrats: She knows and cares about their concerns, and backs that up with action.

Clinton also positioned herself well in Nevada for the general election, should she become the nominee, Fernandez noted. The major Republican candidates either favor Yucca Mountain or have not taken a firm position on the project.

And Clinton put her competitors in a tough position. Her fellow Democrats now must find a way to make their own moves on Yucca without seeming to "me too" Clinton's.

If they agree with the idea of holding hearings, "they will look like they're just following along," Fernandez said, but if they disagree, they risk looking insufficiently tough on Yucca.

The response of one of Clinton's fellow senators and her top opponent for the Democratic nomination illustrated the difficulty.

"Senator Obama doesn't need new hearings to know that he does not support using Yucca Mountain as a nuclear waste site," said Jen Psaki, a spokeswoman for Sen. Barack Obama, D-Ill. "To the extent that hearings would help raise public awareness about the issue, he supports them."

At the same time, by positioning herself as vocal on Yucca, Clinton left herself open to attacks on the issue. One of those came last week, when a Republican senator pointed out that Clinton skipped two hearings on Yucca last year.

Clinton's campaign responded that she was busy with important business on the days in question. And in a local radio interview last week, Clinton said it would have been "a waste of time to ask questions" in the Republican-controlled Congress.

"There was a feeling that, no matter what questions were raised, there was a very strong momentum that the administration and their Republican allies in Congress were attempting to generate to move forward on Yucca," Clinton said on KNPR-FM, 88.9's "State of Nevada."

Things are different now that Democrats are in charge, Clinton said.

Then there is the question of whether Clinton's anti-Yucca position is strong enough for the dump's most ardent opponents. The anti-Yucca purists say that if you really oppose the project, you must also oppose any increase in nuclear energy, which would only produce more waste.

"We shouldn't go down the path (to expanding nuclear power) when we already know it's a failure," said Michele Boyd, legislative director for the energy program at Public Citizen, a Washington, D.C.-based nonprofit opposed to Yucca Mountain.

"We oppose nuclear power because of the cost, the waste, safety, security and proliferation," Boyd said. "We can deal with climate change faster, cheaper and cleaner with renewables and efficiency."

The issue was raised in last week's Democratic debate sponsored by YouTube and CNN, when a questioner opined that nuclear power was a good option for alternative energy and asked the candidates what they thought.

Former North Carolina Sen. John Edwards seemed to take the firmest anti-nuke stand, saying, "I do not favor nuclear power," and explaining his reasons.

Obama took the question next and said, "I actually think that we should explore nuclear power as part of the energy mix."

Clinton's response was, "I'm agnostic about nuclear power. John is right, that until we figure out what we're going to do with the waste and the cost, it's very hard to see nuclear as a part of our future. But that's where American technology comes in. Let's figure out what we're going to do about the waste and the cost if we think nuclear should be a part of the solution."

In the KNPR interview, Clinton said she was "not against" a future for nuclear power.

Boyd wouldn't comment directly on the candidates, but she said there should be no talk about any future for nuclear power. The issue ought to be closed.

"We've been exploring it for 50 years," she said. "We know it's not a solution."

The debate question and its response represent a recent fissure in the environmental movement. In the past, most environmental activists opposed nuclear power, but some now see it as a cleaner alternative to pollution-generating coal-fired power plants.

The state of Nevada's official position is opposed to the Yucca Mountain project but not to nuclear energy.

One of the anti-nuclear purists in Nevada has always been Peggy Maze Johnson. Long Nevada's most vocal anti- Yucca voice as executive director of Citizen Alert, Maze Johnson has always said nuclear power must also be opposed because of the problem its byproducts pose.

Maze Johnson now is on leave from Citizen Alert in order to serve as a paid staffer for the Clinton campaign in Nevada.

In an interview last week, Maze Johnson said she helped advise Clinton on her Yucca announcement. And she defended Clinton's stance on nuclear power.

"She's always been perfect on Yucca Mountain," Maze Johnson said of Clinton.

Asked about Clinton's "agnostic" stance, Maze Johnson said she saw it as amounting to opposition to nuclear power. "That's what she said -- until they deal with the waste, you can't expand it."

Clinton's announcement was exquisitely timed. Senate Majority Leader Harry Reid last year proclaimed the project "dead," and it had lain dormant as an issue for a while; but it recently flared up in the headlines due to a controversy over the use of state water to drill bore holes for research at the site.

In a prepared statement, Reid backed Clinton's call for hearings, saying, "I am convinced Senator Clinton's proposal will help Nevada win the fight to kill the dump once and for all."

Asked what was the point of holding hearings on a dead proposal, a Reid spokesman said vigilance is needed to keep Yucca from coming back to life.

"We all know that the dump will never be built ... but there are a lot of questions about Yucca Mountain that still need to be answered to make sure we continue to go through the process" of quashing it, Jon Summers said.

In her conference call with Nevada reporters on July 20, Clinton, who is famous for doing her homework on complex issues, showed her fluency with the topic of Yucca in answering a question about the proposed hearings.

"Those of you who have been following this may recall that EPA set a rule about acceptable radiation exposure, and that rule in 2001 was overturned by the federal court in 2004, when challenged by Nevada and environmentalists," Clinton said. "The significance of this is that the court ruled that EPA is obligated to set this radiation limit, and has to do so as part of this licensing application process.

"Well, they proposed a revised rule in 2005, but again, Nevada has argued that its limit is dangerously lax, and is about to sue again. They still haven't put out a final rule, and they've been basically unaccountable and not having to answer questions up until now because, as I said, the Republican Congress wasn't willing to ask the hard questions. So we're going to ask the hard questions."