Republican John McCain is all for it. Democrats Hillary Clinton, Joe Biden and Bill Richardson can point to records of opposition to it.

Democrats Chris Dodd and John Edwards now say they are against the repository, but they've supported it in the past. Democrat Barack Obama hasn't had occasion to vote on the issue but says he opposes Yucca.

Republicans Rudy Giuliani and Mitt Romney also have no record on the issue, and they have not indicated opposition to the proposal.

The state is officially against the federal proposal to transport nuclear waste from power plants around the country to a repository in the Nevada desert about 100 miles northwest of Las Vegas.

In Congress, Republicans have generally supported the proposed repository, while most Democrats have opposed it, although there are many exceptions on both sides. All five of Nevada's federal representatives strongly oppose the site.

The issue last came to a vote of the whole Congress in 2002, when both the House and Senate voted to override then-Nevada Gov. Kenny Guinn's veto of the proposal.

For candidates, the issue can be a tricky one. In addition to trying to win the electoral votes of Nevada, a small but critical swing state, they must also campaign in the many states eager to get rid of the waste sitting precariously at the plant sites in temporary storage.

But Nevada advocates insist that it's too dangerous to transport radioactive waste across the country to Yucca Mountain and say candidates should come out strongly against the site.

"Any thinking person running for president of the United States should understand this is not a Nevada issue," said Peggy Maze Johnson, executive director of Citizen Alert. "This is a national issue, because it has to do with the safety of our roadways."

In the 2004 presidential election, Democratic nominee John Kerry said he opposed Yucca and would shut down the project. President Bush since 2000 has said he would base his decision on "sound science."

Advocates such as Maze Johnson consider Bush to have gone back on his word, especially after e-mails surfaced in 2005 showing that scientists at the U.S. Geological Survey were falsifying research data on the site.

The Bush administration has pressed on, but Senate Majority Leader Harry Reid has led the charge to stall and cut funding for the project, and earlier this year he said he considered it "dead."

Maze Johnson said it wasn't quite safe to assume the fight against Yucca is over.

"It's gasping," she said. "I can hear the death rattle, as my Irish grandmother would say, but until it's taken its last gasp, we have to be vigilant."

Maze Johnson said she hoped Giuliani could learn more about the issue and come around.

She criticized Romney's vague promise to base decisions on "sound science and conclusive studies," saying, "That sounds like a nonstatement."

Of Dodd and Edwards' changes of heart on the issue, she said she hoped they'd stay opposed.

"They can't claim to be consistent, but a lot of these senators have learned a lot since that vote in 2002," she said. "Since then, so much more has come out" about the project's risks.

Candidates must answer two more questions as well, she said: What they consider the best alternative to the Nevada repository, and whether they believe in nuclear energy as a source of electricity.

"It's irresponsible for candidates to support expansion of nuclear power when this issue (waste disposal) is not resolved," she said.

On that score the candidates often have a harder time. Biden, for example, said he had no alternative plan to deal with the on-site waste, which experts worry could be a target for terrorist attack; all the Republican candidates and Dodd said they wouldn't rule out expanding nuclear power.

Then there is the question of whether Nevada voters care enough about the issue to base their votes on it.

Statewide polling indicates nearly three-quarters of Nevadans are against the site, but that doesn't mean they'll only vote for an anti-Yucca candidate. McCain, when he visited Nevada last month, noted that Bush won Nevada twice despite not opposing the project.

Asked why Nevadans should support a pro-Yucca candidate, McCain said, "Well, if that's their defining issue then I certainly understand why they wouldn't." But he said he hoped Nevada voters would also consider his stances on other issues.

Republican political consultant Steve Wark said Nevadans aren't focused on Yucca Mountain to the exclusion of all else.

"I have seen many polls going back almost 20 years, and they have consistently shown that voters rank Yucca Mountain at ninth or 10th in importance when compared to other issues," he said. "Obviously, when the question is asked whether or not you'd like to have nuclear waste in your backyard, they all say no, but they are not losing sleep over it."

Gibbons said Nevadans deserve clear answers from all the candidates.

"Yucca Mountain is a bad idea, because Nevada does not need to be a dumping ground for other states' problems. It's scientifically unsafe, and I'm a scientist," said Gibbons, who has a master's degree in geology.

Gibbons said he "absolutely" condemned McCain's stance on the issue, but at least there was no doubt about his position.

"The next president, if they are to get the support of Nevadans, needs to be clear on where they stand," he added. "I don't think it's responsible for any candidate to support it, but every voter in this state has to make that decision for him- or herself."

How do the 2008 presidential contenders stack up on the proposal for a nuclear waste repository at Yucca Mountain, which the state of Nevada opposes? The Review-Journal asked all the candidates who have active campaigns in Nevada where they stand on the issue.

Sen. Joe Biden, D-Del.

RECORD: Opposed Yucca in Senate in 2002.

SAYS: "I have voted against Yucca Mountain on at least three occasions. I oppose it. It's not stable. ... Two reasons. No. 1, the transportation is not safe at this point, and No. 2, all the data I have seen about how stable Yucca Mountain is." Asked if he knew of an alternative way to dispose of nuclear waste, Biden said he did not, although he noted that his state, Delaware, is "surrounded on all sides" by nuclear waste.

Review-Journal interview -- 2/15/07

Sen. Hillary Clinton, D-N.Y.

RECORD: Opposed Yucca in Senate in 2002.

SAYS: "I've long opposed using Yucca as a site for nuclear waste. Yucca Mountain is not a suitable place for long-term storage of our nuclear waste. There are too many unanswered questions about both the geology of the site and integrity of the science done to support the decision to store waste there."

Statement -- 3/6/07

Sen. Chris Dodd, D-Conn.

RECORD: In 2002, issued a news release headlined, "Dodd supports moving nuclear waste out of Connecticut to Yucca Mountain site," but voted against a procedural motion to go forward with the project.

SAYS: Now says he merely supported "the idea of coming up with a facility."

"The latest studies on this stuff have indicated serious geological issues, transportation issues, and I'm satisfied at this point that it does not make sense. Yucca Mountain is not a good answer to this."

Review-Journal interview -- 4/14/07

Former Sen. John Edwards, D-N.C.

RECORD: Supported Yucca in Senate in 2002.

SAYS: "Over time it's become clear that the science is unreliable. That seems to be now the consensus of the scientific community. There's also been serious allegations about fraud and misrepresentation in some of the scientific documents, and I've also become more concerned over time with the transport of nuclear waste across the country, particularly with what's happened with the threat of terrorism." Said he is against expanding nuclear power.

Review-Journal interview -- 4/30/07

Former New York City Mayor Rudy Giuliani, Republican

RECORD: None

SAYS: "One of the things you've got to be real careful about with nuclear power is you've got to make sure it's really, really safe. Frankly, some of the problems that have occurred with Yucca Mountain are matters of grave concern, so you'd have to take a good look at that." Would not rule out continuing to pursue the repository.

Review-Journal -- 3/29/07

Sen. John McCain, R-Ariz.

RECORD: Supported Yucca in Senate in 2002.

SAYS: "I think we have to have a place to store the waste. I think that nuclear power has got to be a vital part of our effort to be independent of foreign oil, and I think it's (Yucca Mountain) a suitable place for storage." McCain said he had not been convinced that the site isn't safe or that transporting the waste to the site was unduly dangerous.

Review-Journal -- 4/20/07

Sen. Barack Obama, D-Ill.

RECORD: None.

SAYS: "After spending billions of dollars on Yucca Mountain, there are still significant questions about whether nuclear waste can be safely stored there. So, at this time, Senator Obama can't support the Yucca Mountain project and believes we should redirect spending on alternatives, such as improving the safety and security of spent fuel at plant sites around the country. At the same time, we should continue looking for a safe, long-term disposal solution based on sound science."

Statement, campaign spokesman Bill Burton -- 2/18/07

New Mexico Gov. Bill Richardson, Democrat

RECORD: As energy secretary under President Clinton, says he prevented the project from continuing.

SAYS: "If I'm president, I would terminate it, because I believe it's unsuitable. When I was there (secretary of energy) many of my scientists wanted me to declare it suitable and there were significant water problems, there were significant other environmental, scientific problems that we hadn't worked out. ... I'd always voted against it in Congress. My record is clear. I don't have like, two positions, like other candidates."

Review-Journal interview -- 4/30/07

Former Massachusetts Gov. Mitt Romney, Republican

RECORD: None.

SAYS: "While nuclear power is one of our most promising avenues for developing energy independence from foreign oil, it also presents obstacles such as how to dispose of spent nuclear fuel. To overcome these obstacles, the governor believes decisions must be made on the basis of sound science and conclusive studies instead of political calculations."

Statement, campaign spokeswoman Sarah Pompei -- 4/24/07