The numbers weren't too different when only Clark County residents were asked. Again, 23 percent said Yucca would be a major influence; 41 percent said it would have no influence; and 34 percent said it would have some influence.

"Obviously it's going to affect different voters in different ways," said Brad Coker, managing partner of the independent firm that conducted the telephone survey for the Review-Journal, Mason-Dixon Polling & Research Inc., based in Washington, D.C. "If you look at who it will have a major impact on, it is primarily Democratic voters."

Coker's comments came Thursday, the day that Democratic presidential candidate Barack Obama's campaign launched its second television ad on the Yucca issue. The new ad takes a jab at his Republican opponent: "If you don't want nuclear waste here, you don't want John McCain here," referring to the White House.

McCain, who historically has been a strong supporter of the Yucca Mountain Project, has added a recent caveat to his stance, saying in order for the project to go forward it must meet all safety and environmental standards.

About 36 percent of the Democrat respondents said Yucca Mountain would have a major influence on their choice for president. The statewide results have a margin of error of plus or minus 5 percentage points. The Clark County results have a margin of error of plus or minus 6 percentage points.

Only 8 percent of the Republican respondents said entombing the nation's highly radioactive waste in Yucca Mountain, 100 miles northwest of Las Vegas, would have a major impact on their vote.

In a similar poll in June, 45 percent of Nevada respondents said Yucca Mountain would have no influence on their vote for president; 14 percent said it would have a major impact; and 38 percent said the nuclear waste project would have some influence.

On a related question, one about positions on storing nuclear waste in Yucca Mountain, most Nevadans -- 58 percent -- opposed the government's disposal plans, mirroring the 58 percent in June who said they want to fight the Yucca Mountain Project.

That's roughly the same result as four years ago when a Mason-Dixon poll for the Review-Journal found that 55 percent of Nevadans want to fight Yucca Mountain, while 38 percent favored making a deal for benefits to let it go forward.

In this month's regional poll, 51 percent of the respondents from Utah opposed storing nuclear waste in Yucca Mountain, but only 20 percent from Arizona opposed the plan. Fifty-five percent of the Arizona respondents support the Yucca Mountain Project.

Don Ashley, who has lived in Las Vegas for 71 years, was among the 38 percent of the respondents who said the Yucca Mountain issue wouldn't influence whom he wants in the White House.

"I don't mind if they open Yucca Mountain up for a dump," Ashley said. "Somebody's got to store it, and the government would pay us lots of money for it. I think it's time for people to realize that we're going to get it sooner or later."

Carole Manshreck moved to Las Vegas 20 years ago from Chicago. As a respondent in the poll, she said Yucca Mountain would have some influence on whom she votes.

"I don't want it here," she said about spent nuclear fuel. "It's better off staying right where it is than moving it. Why would you move something that's so toxic?

"McCain doesn't want it in his backyard," Manshreck said of the Arizona senator.

Coker said the Yucca Mountain issue might make a difference in whom independent voters choose for president. About 26 percent of them are undecided.

In the poll, more than two-thirds of the independents -- 69 percent -- indicated Yucca Mountain would influence their decision on the next president. In all, 23 percent of the independents said Yucca Mountain would make a major influence on their vote, and 46 percent said it would have some influence.

On a related nuclear power issue in Western states, 58 percent of those polled in Nevada, Arizona, Colorado, New Mexico, Utah and Wyoming supported increased uranium mining to expand nuclear power. Two-thirds of Wyoming respondents, 66 percent, supported increased uranium mining. In Nevada, 58 percent, supported it and 29 percent opposed it.

Contact reporter Keith Rogers at krogers@reviewjournal.com or 702-383-0308.