Clinton would get 37 percent of the vote if a Democratic caucus were held today, holding a healthy lead over John Edwards (13 percent) and Barack Obama (12 percent), according to the poll.

"Hillary is the clear front-runner on the Democratic side," said Brad Coker, managing partner of Mason-Dixon Polling & Research Inc., which conducted the survey. "The Republican race is just wide open. There's no clear favorite."

The poll, conducted Monday to Wednesday statewide, surveyed Republican and Democratic partisans who said they planned to participate in the 2008 presidential nominating caucuses. Three hundred voters were surveyed on each side. The poll carries a margin of error of plus or minus 6 percentage points.

At this point, eight months before the contests that will help determine the nominees, such numbers are highly preliminary and can't be considered predictive, Coker noted.

But they serve as a benchmark against which to measure candidates' movement up or down in future polls. And given Nevada's new status hosting second-in-the-nation nominating caucuses on both the Democratic and Republican sides, polls here will be closely watched, he said.

On the Democratic side, Clinton has a more formidable lead in Nevada than in most national polls, many of which have shown Obama creeping up on the New York senator. For example, an NBC News/Wall Street Journal poll in late April put Clinton at 36 percent, Obama at 31 percent and Edwards at 20 percent.

That may reflect the fact that Obama has made few trips to Nevada and hasn't seemed to focus on the state, said University of Nevada, Reno, political scientist Eric Herzik.

Obama traveled to Las Vegas in February and March, but he has not been to Northern Nevada. Clinton and Edwards have both made multiple trips to Northern and Southern Nevada, most recently last weekend.

Clinton also boasts the support of influential Nevada figures including Clark County Commission Chairman Rory Reid and former Attorney General Frankie Sue Del Papa.

"Hillary Clinton was the favorite going in, and she's done nothing to hurt herself, particularly in Nevada," Herzik said. "She's been here a few times, and she has a strong organization."

Edwards, however, can't be happy about his low level of support in Nevada, a state where his aggressive pitch to organized labor ought to be an advantage, said Larry Sabato, director of the Center for Politics at the University of Virginia.

"This is really bad news for Edwards," Sabato said. "Nevada is supposed to be one of his stronger states because of labor. That's remarkably low for him."

Prospective candidates who haven't yet said they're going to run were included in the poll, among them, Al Gore, who got 9 percent. Gore may have taken votes that would otherwise have gone to Edwards or Obama, Coker noted.

New Mexico Gov. Bill Richardson, who has mounted an aggressive push in Nevada, came in fifth in the poll with 6 percent. National polls have generally put him at 2 or 3 percent.

"He's a Westerner. His campaign has been selling us analysts on the idea that he's going to be the regional Western candidate, but so far he's not doing so well," Sabato said. "Six percent is double his national number, but so what? It's still 6 percent."

On the Republican side, former New York City Mayor Giuliani leads most national polls, followed by McCain, Thompson and Romney. The NBC News/Wall Street Journal poll put Giuliani at 33 percent, McCain at 22 percent, Thompson at 17 percent and Romney at 12 percent.

Thompson, the "Law & Order" star and former Tennessee senator, has not yet entered the race.

Those national poll numbers are seen as very soft and subject to fluctuation as Republican voters evaluate a wide-open field. Nevadans' answers reflect that uncertainty, Herzik said.

"There is no clear Republican favorite, in Nevada or nationally," he said. "This race is anyone's to win."

Republicans, he said, are behind Democrats in campaign terms, particularly in Nevada, where the decision to hold an early nominating caucus was made just last month. Democrats have been planning their Jan. 19 caucus, scheduled for after the Iowa caucuses and before the New Hampshire primary, since last August.

"Republicans will start showing up in Nevada, but at this point they're behind in the process," he said.

The Review-Journal poll was taken before Thursday night's debate among Republican candidates. Another candidate who hasn't announced whether he's running, former House Speaker Newt Gingrich, also made a dent in the Review-Journal poll, with 7 percent support.

McCain has made campaign appearances in Northern and Southern Nevada in recent weeks. Giuliani raised more money in Nevada than any other candidate of either party in the first quarter, and he has some high-profile supporters here such as state Senate Majority Leader Bill Raggio and U.S. Rep. Jon Porter.

Romney has yet to campaign in Nevada. The former Massachusetts governor's only trip here was a private fundraiser in Las Vegas in March.

Sabato noted that 28 percent of Nevada Republicans said they were undecided, compared to 19 percent of Democrats.

"It's a jump ball, nationally and in Nevada," he said. "Republicans are much less decided than Democrats."