A new television ad by a national Republican group blasts independent U.S. Senate candidate Angus King and Democrat Cynthia Dill for their support of industrial wind power.

The 30-second spot is part of a reported $600,000 ad buy from the National Republican Senatorial Committee to support the GOP’s Senate candidate, Charlie Summers.

The ad, titled “Caught,” builds off recent statements by Republicans who say King benefited from a federal loan guarantee program that invested billions of dollars in wind power projects.

The ad says King, a former partner in Independence Wind, used his “political connections” to win a taxpayer-backed $102 million federal loan guarantee for the 22-turbine, 50-megawatt Record Hill project last year.

The ad goes on to say that the loan program came under scrutiny by the House Oversight Committee, an investigative panel on which Republicans hold the majority of seats.

The King campaign fired back at the ad Thursday, partly by saying King sold his interest in the Record Hill project in January 2011, before the project received federal financing.

The ad also criticizes Dill for her “liberal policies,” saying she supports President Obama’s “tax increases” and stimulus spending.

Dill criticized the ad in an email Wednesday, even before the commercial aired. “Let’s tell these charlatans that they cannot ‘purchase’ the U.S. Senate election in Maine,” she said.

The two-pronged attack by Republicans is an apparent attempt to lump King and Dill as the two liberal candidates in the race.

The new ad’s attack on King’s involvement in the wind power industry was not unexpected. Republicans have taken aim at King’s career in wind power since he entered the race.

Shortly after announcing his candidacy in March, King transferred his stake in Independence Wind to his business partner, Rob Gardiner, former president of the Maine Public Broadcasting Network.

King said he wanted to avoid any conflict of interest while discussing federal energy policy. Republicans said King sold his interest because of the Oversight Committee investigation, which was sparked by the bankruptcy of a federally subsidized solar company named Solyndra.

The committee’s staff issued a report in March questioning whether Record Hill and other projects in the loan guarantee program received federal help they did not need or deserve. The committee review continues, a spokesman said.

Republicans said King’s sale of his wind power interests two days before the report was issued suggested he wanted to distance himself from the project.

King has said that the release of the report was a coincidence and that he had decided to sell his stake before he knew anything about the congressional investigation.

King has denied using influence to win financing for the project. He also said taxpayers and consumers are benefiting from the electricity being generated by Record Hill and the owners are repaying the loan as promised.

On Thursday, King spokeswoman Crystal Canney said King actually sold his stake in the Record Hill project in January 2011. His payment was contingent on the successful completion of the project, which started generating power this spring.

King remained a partner in Independence Wind, which is developing a second wind farm project, until this spring, when he decided to run for the Senate.

As for the new ad, Canney said, “Clearly the Republicans don’t think they have a candidate that brings much to the table because they’re spending an awful lot of money running pro-Democratic ads and then anti-Democratic and anti-independent ads.”

“As Angus said today, the people running these ads don’t give a damn about Maine, and he’s absolutely right,” she added.

Some political observers have wondered whether the National Republican Senatorial Committee’s involvement indicates that the race between King and Summers is tightening. No independent polling has been done to measure the current status of the race.

Others have suggested that the committee’s attempt to influence the race reflects growing concern among Republican strategists that the party is losing its advantage to gain a 51-seat majority in the U.S. Senate. The committee is running ads in Maine, North Dakota and Montana.

The King campaign had been bracing for the ad and readying a response. The campaign has been promoting a spot in which King tells viewers “that some folks from away” are spending big money to cast him as a Godzilla-like monster.

“They may think we were born at night up here, but it wasn’t last night,” King says.

— Staff Writer John Richardson contributed to this report.

Staff Writer Steve Mistler can be contacted at 791-6345 or at:

smistler@pressherald.com