Sen. Dean Heller (R-Nev.) leads Rep. Shelley Berkley (D-Nev.) by 48 percent to 42 percent, according to a poll conducted by Republican pollster Glen Bolger.

The Heller-Berkley matchup is expected to be one of the hardest fought in the country, and Democrats view it as one of their two best pickup opportunities, along with Massachusetts.

Heller leads Berkley by 17 points in Washoe County, a bellwhether area that he represented in Congress. President Obama carried the county by 13 points in 2008, when he won the state by a similar margin; Senate Majority Leader Harry Reid carried it by five points when he won reelection with that same margin in 2010.

While partisan polls usually have a tilt towards their party, the Las Vegas Sun's political guru, Jon Ralston, points out that he has been "spot on" in predicting Nevada elections in the past.

The poll of 500 likely voters, conducted for the Retail Association of Nevada, had a margin of error of plus or minus 4.38 percent.