Republican challenger Dean Scontras has moved slightly ahead of incumbent U.S. Rep. Chellie Pingree, although they remain in a statistical dead heat in their 1st Congressional District race, according to the fourth and final wave of The Maine Poll.

Scontras, an alternative-energy entrepreneur from Eliot, received 45 percent of respondents’ support compared to 41 percent for Pingree, in the poll conducted Wednesday and Thursday for MaineToday Media by the Portland research firm Critical Insights.

The sample size of 295 likely voters yields a margin of error of plus or minus 5.7% at a 95 percent confidence level. A week ago, Pingree led Scontras by five points, 45-40, which also signaled a statistical tie.

Two earlier polls showed Pingree, seeking re-election for the first time, leading by double-digit margins.