Democrat Martin Heinrich maintains a narrow lead over his Republican opponent, Darren White, in the race for New Mexico’s 1st Congressional District in an internal poll released today by the Heinrich campaign.

Heinrich, a one-term Albuquerque city councilor making his first bid for national office, leads 48-42 percent over White, the Bernalillo County sheriff, according to a poll of 450 likely voters taken earlier this week by Greenberg Quinlan Rosner Research. When undecided voters were asked how they were leaning in the race, Heinrich hit 50 percent, to White’s 45 percent, the pollsters say. The margin of error was 4.6 percent.

Greenberg Quinlan Rosner, whose Web site notes, “We give Democrats the edge over their opponents, taking on and winning the toughest races,” conducted a similar poll for the Heinrich campaign in July that showed a closer race. It had Heinrich leading 47-44.

As the Independent reported in July, the White campaign quickly knocked the Greenberg poll, and revealed its own internal poll showing the Republican with a 47-41 percent lead. Last fall the same polling group, Public Opinion Strategies, had White ahead by 18 points.

The only independent poll in the race, conducted by the Capitol Hill newspaper Roll Call during the Democratic National Convention in late August, gave Heinrich 51 percent of the vote to White’s 46. The margin of error was 4 percent.

Heinrich spokeswoman Angela Barranco said the latest numbers show the campaign is resonating with CD1 voters. “It’s great news that Martin is not only holding onto his lead but expanding it,” she said. It also confirms the campaign strategy for the next six weeks, Barranco added. “We’re just going to keep on doing what we’re doing.”