It’s tough to predict what will happen in tomorrow’s Nevada caucuses since there’s never been a crucial high-turnout there, but the predictions continue nonetheless.

A Las Vegas Review-Journal poll released today finds that Republican Mitt Romney leads his closest opponent by 15 points. He tops John McCain 34 percent to 19 percent.

Unlike other GOP candidates, Romney has invested extensively in the state and although Rudy Guiliani led in earlier Review-Journal polls as recently as December, Romney is now Republican caucus-goers’ favorite candidate. He’s the pick on every issue and for every voter group except those describing themselves as born-again Christians, who favored Mike Huckabee.

For the Democrats, Hillary Rodham Clinton is ahead of Barack Obama by 9 points, 41 percent to 32 percent. Clinton continues to maintain the edge she’s had in most state polls despite Obama’s intense efforts to compete in Nevada and his recent union endorsements.

After polls failed to predict the winners of the New Hampshire primaries, concerns linger that it will be hard to accurately poll for Nevada’s first-time early caucus, since it is difficult to determine who will attend.

“It certainly presents some interesting challenges, but I don’t think it’s impossible to do,” said Mason-Dixon Polling & Research pollster, Brad Coker. “It took a lot of work, but I think I figured it out. I’m pretty comfortable with the way we did it.”

The poll of 500 likely caucus-goers for each party was conducted by Mason-Dixon Polling & Research Inc. from Monday through Wednesday and has a margin of error of 4.5 points.