Three different candidates would win Republican contests: former New York City Mayor Rudy Giuliani in Nevada, former Arkansas Gov. Mike Huckabee in Iowa and South Carolina, and former Massachusetts Gov. Mitt Romney in New Hampshire.

In Nevada, Clinton's seemingly iron grip on the Democratic caucus has slipped, but her 8-point lead here is her widest margin over Illinois Sen. Barack Obama among the four states.

Giuliani leads Romney here by 5 percentage points, but they are followed closely by a nationally surging Huckabee, the previously all-but-unknown former preacher who has not set foot in the state.

"It's obvious that Huckabee, on the Republican side, has made a splash," said Brad Coker, managing partner of polling firm Mason-Dixon Polling & Research Inc. "On the Democratic side, Obama and Clinton are getting closer. The inevitability factor for Hillary is gone, and Nevada, which looked like a built-in firewall for her, isn't there anymore."

Mason-Dixon conducted the four polls simultaneously last week for the Review-Journal, McClatchy Newspapers and MSNBC. The presidential primary questions carry a margin of error of plus or minus 6 percentage points in Nevada, 5 points in the other three states.

The Nevada poll also matched up Clinton and Obama with each of the top five Republicans in a hypothetical general-election contest. The Republican would win almost all of those face-offs. But Obama would be more competitive than Clinton, by an average of nearly 10 percentage points, and Obama would tie Romney and beat Huckabee.

Among the Democrats, Clinton in Nevada captures 34 percent of likely caucus-goers. Obama is gaining on her, with 26 percent.

No other candidate registers in double digits. Former North Carolina Sen. John Edwards gets 9 percent, while New Mexico Gov. Bill Richardson earns 7 percent.

Although still in the lead, Clinton has a much smaller margin on her nearest rival than in previous statewide polls. In the Review-Journal's last poll, conducted in October, she had 39 percent to Obama's 21 percent.

Other organizations' polls have even shown Clinton above 50 percent in Nevada, a remarkable feat in a multicandidate race.

With widespread support among Nevada's political establishment, Clinton previously seemed to have a lock on the state's first early contest, scheduled for Jan. 19.

"This is an interesting fall by Hillary Clinton," said Eric Herzik, a University of Nevada, Reno political scientist. "The traditional wisdom is that this should be no surprise. As the election date gets closer, races tend to get closer. Big leads rarely sustain themselves."

Nonetheless, Herzik said, Clinton should be able to pull out a win in Nevada.

"That would be a terrific collapse, given her organization, her money, all the people backing her and her big lead early on," he said. "Obama's the fresh face, and he's got some momentum right now. She's off her game right now. But it would be amazing if she didn't win here."

Edwards claims the most support from Nevada union members, who are expected to be a major force in the caucus, but he just doesn't have the campaign apparatus to make a dent in the polls, especially when all the focus has been on the sparring between Clinton and Obama, Herzik said.

"I don't understand why John Edwards is not capturing the hearts and minds of Democratic voters," he said. "He just has not. He hasn't in Nevada; he hasn't nationally."

The Republican field has been unsettled here, with Giuliani leading the October Review-Journal poll and Romney leading one conducted in June. Giuliani now has 25 percent and Romney 20 percent.

But the big surprise is Huckabee, who registers 17 percent of likely Republican caucus-goers despite having no presence in Nevada. He has not been to the state during the campaign. He doesn't have staff or a volunteer group here and has not paid for advertising. He is not publicly championed by any Nevada officials.

In previous Review-Journal polls, Huckabee pulled 2 percent or 3 percent of the Republican vote.

Herzik said Huckabee is getting a Nevada bounce that echoes a sudden surge in national attention based on his debate performance and appeal among Christian conservatives dissatisfied with the rest of the field.

Among Nevada Republicans, evangelical and social conservatives aren't the majority, and Herzik said Huckabee will likely fade here when his less than hard-line stances on taxes and immigration come to voters' attention. But for now, he's the raft Nevada Republicans are grasping at in a sea of uncertainty.

"A few months ago, Fred Thompson was the flavor of the month," Herzik said. "He's run a lousy campaign, and now he's almost gone. His drop is reflected in Huckabee's rise. The standbys are Giuliani and Romney, but no Republican has seized this race by the throat. Or the heart, I guess is a better way of putting it."

Thompson, the actor and former Tennessee senator, is first among the also-rans in the new Nevada poll, with 9 percent support. Arizona Sen. John McCain has 7 percent and Texas Rep. Ron Paul 5 percent.

Herzik said those numbers are but a snapshot of a very fast-moving, fluid situation. He said Paul especially could show strength if his very committed supporters, many of them new voters or new Republicans, make it to the caucus in force.

"Ron Paul could get 5 percent or he could get 25 percent," he said. "There's no telling with him."

In the other states:

Iowa features a tight Democratic field with Clinton clinging to a lead that is within the margin of error. It's Clinton 27, Obama 25, Edwards 21 among likely participants in that crucial No. 1 contest, scheduled for Jan. 3.

The Republican side is a different story, and an exception from the rule of tight Republican races. Huckabee is running away with 32 percent of the vote, while Romney has 20 and Thompson 11.

Despite being the consistent national front-runner, Giuliani is in fifth place in Iowa with just 5 percent, behind McCain's 7 percent.

In New Hampshire, Clinton again hangs onto a slim lead in a state whose polls she has mostly dominated. She has 30 percent of the vote compared to Obama's 27, while Edwards has 10 percent of likely voters in the Jan. 8 primary.

New Hampshire is seen as Romney's backyard, and he leads there with 25 percent. Giuliani has 17 percent and McCain 16, while Huckabee pulls a surprising 11 percent in a state where, like Nevada, Republicans tend to be more anti-tax and less religious.

South Carolina partisans vote on two different dates: Republicans on Jan. 19, the same day as the Nevada caucuses, Democrats on Jan. 26.

This is where the Republican field most resembles a bunched-up line of Christmas Eve shoppers. The five leading candidates are within 10 percentage points, with man-of-the-moment Huckabee in the lead at 20 percent.

Giuliani has 17 percent of likely Republican primary voters, Romney 15, Thompson 14 and McCain 10.

Meanwhile, among the Democrats, 28 percent of South Carolinians go for Clinton, 25 for Obama and 18 for Edwards.

National political analyst Jennifer Duffy, of the nonpartisan Cook Political Report newsletter, noted that the order of the contests will be crucial.

What happens in Iowa will affect what happens just five days later in New Hampshire; developments there will color the races in Nevada and South Carolina.

Republicans also have a Michigan primary to worry about on Jan. 15; most Democrats aren't participating in it.

Duffy noted a few surprises among the barrage of numbers. Giuliani has never expected to do well in socially conservative Iowa, but fifth place and 5 percent is too poor a showing to explain away.

"If he comes in fifth, it's going to be five days of very bad news until New Hampshire," Duffy said. "He's got to perform well enough to not be written off by the media and survive to February 5," the super-duper Tuesday when Giuliani hopes to win some big states.

Duffy said Huckabee is riding high especially after a widely watched and discussed debate Nov. 28, in which he got off several zingers.

But independent organizations such as the anti-tax Club for Growth are beginning ferocious ad campaigns against him, which could strike a chord in New Hampshire and Nevada. And despite his popularity, he still lacks campaign funds and organization.

Duffy said the Nevada general-election matches reinforce the idea that Clinton lacks "electability" because many people would vote for any candidate just to vote against her.

However, Clinton often beats the Republican candidates in national head-to-heads, she said. That indicates that Nevada may be more conservative, or perhaps just more anti-Clinton, than the nation as a whole.

Unlike Clinton, "Obama would be a competitive candidate right away," Duffy said. "He would start out a little bit behind, but he'd be viable -- more viable, apparently, than Clinton."

McCain, who has been all but written off based on his fade from the primary contest, polls the strongest against both Democrats.

"That's a little bit bizarre for a guy polling at 7 percent in his own party," Duffy said.

It could be a remnant of McCain's old image as the independent, straight-talking maverick who appealed to independent voters and some Democrats.

"The conservatives who are inclined to go to a Republican caucus are not McCain voters," she said. "They'd pick him over a Democrat given the opportunity. But for him to get to that point would be the comeback of all time."

Contact reporter Molly Ball at mball@ reviewjournal.com or (702) 387-2919.