A $400,000 advertising campaign targeting independent candidate Angus King is part of a multi-state effort by the U.S. Chamber of Commerce to win a Republican majority in the U.S. Senate.

But it’s a new experience for Maine, and a lot of people will be watching to see if it works here.

The chamber will likely conduct some polling in early or mid-August to see if the ads succeed in cutting into King’s 25-point lead in the polls. If they work, lots more could follow, experts say.

That would be good news for Republican Charlie Summers, who won the chamber’s endorsement and is polling in second place.

It also might be good news for Democrat Cynthia Dill, said Ron Schmidt, associate professor of political science at the University of Southern Maine.

“It could wind up being a flag to both the GOP and the Democrats to be more aggressive if it works,” he said. Schmidt has his doubts, however.

“Negative ads haven’t shown themselves to be particularly effective here, especially when paid for and run by outside groups. And it could wind up playing into Angus King’s narrative” about special interests and partisanship ruining politics, Schmidt said.

Michael Franz, associate professor of government at Bowdoin College, said money goes a long way in Maine’s relatively cheap media market, so it makes sense that the chamber or other GOP-backers would try.

“There’s no need to write this race off without trying,” Franz said. “Mainers would probably say they would be unlikely to be influenced and that may be true, but my guess is that Maine people are as persuadable as everywhere. … It’s entirely possible that it could strike a chord with voters.”

Ethan Strimling, a former Democratic state senator from Portland, said it’s a big advertising buy for Maine and will reach a lot of people. “If the buy is that big it probably will move the needle,” he said.

Charlie Webster, chairman of the Maine Republican Party, said he’s confident King’s lead will fade as voters are reminded about his record. But he doesn’t put a lot of faith in the chamber’s initial attempt.

“It wasn’t as well done as I’d like to see, but I’m sure there will be others,” Webster said.

STATE CHAMBER SAYS ‘THAT’S NOT US’

The Maine State Chamber of Commerce, meanwhile, wants Maine businesses and voters to know that it has nothing to do with the new anti-King ads.

“People do get confused when the word chamber is used that we were part of that decision-making process,” said Dana Connors, president of the Maine chamber. “We don’t get involved in the endorsement of candidates at the national level. … We in no way are involved and we do want to make sure people understand the difference.”

As it happens, Connors was chairman of the Angus King transition team when King became governor in 1995. Then, as president of the chamber, Connors worked with the King administration on economic development issues.

“I would be less than honest if I didn’t say that our experience and our relationship with Angus King from the business community’s perspective was very strong. He was open to our opinions. He focused on business issues,” Connors said.

So, is that an endorsement? “That in no way should suggest we are endorsing a candidate,” he said.

NATIONAL ACTIVIST MAKES PLEDGE

Tim Gill, the Colorado software developer and national donor to gay rights causes, has agreed to donate up to $100,000 to the group attempting legalize same-sex marriage in Maine.

The pledge is a matching challenge. Gill, who made his fortune as the head of Quark Inc., has agreed to match every donation up to $100,000 to the group Mainers United for Marriage through Aug. 10.

“I believe Maine is well-positioned to make history this November. That’s why I’m investing in this campaign early when contributions can have their greatest impact,” Gill said in a statement. “There’s a lot of work left to do, but I think Maine has a clear path to victory if others join me in helping them secure the resources they need to win today.”

The challenge makes Gill the latest high-profile donor to the group supporting a referendum to legalize same-sex marriage in Maine. Others include billionaire hedge fund manager and Republican donor Paul Singer and Chris Hughes, the co-founder of Facebook and current owner of the The New Republic magazine.

Gill, who is gay, is a longtime gay rights advocate. In 2005 he started the nonprofit Gill Action Fund to promote LGBT causes.The Colorado resident was once considered the nation’s largest donor to causes affecting the LGBT community, including laws that would allow gay couples to marry.

Gill has also played a large role in Colorado politics and has contributed significant amounts of money to help Democrats get elected to that state’s legislature.

DILL’S FUNDRAISING GETS ATTENTION

Cynthia Dill’s use of the Aurora, Colo., movie theater shootings to raise funds for her U.S. Senate campaign got the attention of U.S. News and World Report.

The blog post — titled “Maine Democratic Lawmaker Uses Aurora Shooting to Drum Up Cash” — notes Dill is “notoriously outspoken” and cites a fundraising email from her U.S. Senate campaign that talks about murdered children and weeping mothers, and asks for $100 donations.

Dill issued a call for stricter gun control laws in the wake of the massacre and was criticized by at least one opponent for politicizing the incident. She told U.S. News the strong language was necessary given the issue and that the fundraising appeal was an opportunity to restate her support for gun control.

Staff Writer John Richardson can be reached at 791-6324 or at:

jrichardson@pressherald.com

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

smistler@pressherald.com