Despite nearly $2 million of negative television advertising aimed at him, former Maine governor Angus King appears to be holding on to a double-digit lead in the race to replace retiring Sen. Olympia Snowe, R-Maine.

A poll released Thursday by Rasmussen Reports, a conservative-leaning polling agency, suggests King, an independent, is favored by about 45 percent of Maine voters as the final month of the campaign approaches.

Republican candidate Charlie Summers, Maine’s secretary of state, was favored by 33 percent of the 500 voters polled, while Democratic state Sen. Cynthia Dill of Cape Elizabeth was trailing with 12 percent. The poll had a 4.5 percent margin of error. 

Polls released earlier in September by Public Policy Polling and the Maine People’s Resource Center also suggested King was leading the race.

The Maine People’s Resource Center poll surveyed 856 registered voters. It suggested King would win with 43 percent of the vote, followed by Summers with 28 percent and Dill with 15 percent.

The poll released by the North Carolina-based Public Policy Polling suggested support for King at 35 percent, for Summers at 28 percent and for Dill at 14 percent.

Thursday’s numbers reflect the third poll this month that shows King’s support softening from the high of 55 percent he enjoyed in June, shortly after he announced he would seek election to Snowe’s seat.