A Republican poll released today found appointed Sen. Dean Heller (R) ahead of Rep. Shelley Berkley (D) by 6 points in a 2012 Senate race matchup.

Heller took 48 percent to Berkley’s 42 percent in the poll, reported by the Las Vegas Sun’s Jon Ralston. It was conducted Wednesday and Thursday for the Retail Association of Nevada by Glen Bolger of Public Opinion Strategies, included 500 likely voters and had a 4-point margin of error.

One major area of concern for Berkley is Heller’s 17-point lead in Washoe County, which along with Las Vegas’ Clark County is a must-win for Democratic statewide candidates. State Treasurer Kate Marshall (D) also lost Washoe in last week’s 2nd district special election.

This Senate race is expected to be among the most competitive in the country next year, and Roll Call Politics currently rates it a Tossup.