A new internal poll conducted for former North Dakota Attorney General Heidi Heitkamp found the Democrat with a 4-point lead in the state’s open-seat Senate contest.

Heitkamp led Rep. Rick Berg (R) 48 percent to 44 percent with 7 percent undecided. The edge, according to a polling memo from the Mellman Group, stems from Heitkamp’s 23-point lead among independents.

In a state that Republican presidential nominee Mitt Romney is expected to carry by a significant margin, Heitkamp also pulled 11 percent of the Republicans surveyed. She led by 24 points among voters who had already cast their ballots.

The survey of 600 likely voters was taken Oct. 21-24 with a 4-point margin of error.

Roll Call rates the race for the seat of retiring Sen. Kent Conrad (D) as a Tossup.