Presidential candidate John Kerry (search) has opened a 10-point lead over rival Howard Dean (searchin a poll of likely voters in New Hampshire's Democratic primary, according to a survey released Wednesday.

Once statistically tied for the lead, Kerry has moved ahead with 28 percent while Dean has lost ground and stands at 18 percent, the American Research Group (search) poll found. The advantage for the Massachusetts senator is the largest since Kerry held a 12-point lead over Dean in January, a gap that closed during the spring.

Kerry held a commanding lead among registered Democrats likely to vote -- 31 percent to 16 percent -- over Dean, the former Vermont governor. Among undeclared voters, or independents, Dean led Kerry, 26 percent to 15 percent. Independents can vote in the Democratic primary in the state.

Almost a fourth of those polled, 23 percent, were undecided, a slight increase from May. Sen. Joe Lieberman of Connecticut, who led all rivals with 100 percent name recognition, was at 11 percent, and Rep. Dick Gephardt of Missouri was at 10 percent.

Sen. John Edwards of North Carolina was at 4 percent, and Sen. Bob Graham of Florida was at 2 percent. Carol Moseley Braun, Rep. Dennis Kucinich of Ohio and Al Sharpton were at 1 percent, as was retired Army Gen. Wesley Clark, who has not announced his candidacy.

The poll of 600 was taken Saturday through Tuesday and had an error margin of plus or minus 4 percentage points.