Updated 5:04 p.m. | The National Republican Senatorial Committee launched a new ad today against Maine Senate frontrunner Angus King (I), one of at least three outside groups that have gone negative on the two-term former governor.

But if the barrage of negative ads running against King bothers him, he did not reveal such feelings in an interview with Roll Call this afternoon.

“I’m a walking economic development project for Maine,” King joked, noting all the money coming into the Pine Tree State’s economy on behalf of outside groups trying to make sure he doesn’t win.

“They’re building a statue of me in the lobby of Channel 6,” King added, laughing, referring to the Portland, Maine, NBC affiliate.

But during a 20-minute discussion on his campaign, King admitted that the ads have had an effect and tightened his race with Republican Charlie Summers and Democrat Cynthia Dill to fill the open seat being vacated by retiring Sen. Olympia Snowe (R).

“The polls have tightened,” he said. “I don’t think I’d be honest if I didn’t say people being pounded every night by being told that I’m a big spender or I blast mountain tops or whatever it is isn’t gonna have some impact.”

Two recent public polls showed King with 8-point and 16-point leads among likely voters and registered voters, respectively, over Summers. Dill trailed both candidates by a substantial margin.

“I suspect the real number is between 15 and 20” points, he said, noting that such a margin could either be interpreted as a decline from where he was or that his campaign is in really good shape.

“Most people in the country would be pretty happy with a 15-point lead right now. Ask Tim Kaine how he would feel about a 15-point lead,” King said.

In his announcement for Senate, King pledged to eschew negative advertising. “You will not see a single negative ad come out of this campaign,” he said at the time to applause.

Does he still stand by that pledge?

“Yes. Yes,” he said.

But King made clear he wouldn’t be a wallflower when it came to talking about his opponents’ positions or pushing back against attacks. “I can go negative against their negative ads. I’ve said from the beginning that I’m not going to go negative against my opponents, but that doesn’t mean I can’t push back against this nonsense that’s coming from people who don’t give a damn about Maine and don’t know Portland from Presque Isle.”

(Portland is the state’s largest city. Presque Isle is a small city 286 miles to the north, close to the border with Canada.)

King said there were differences between him and his opponents that were emerging. “We’re certainly going to talk about those in the press and possibly on television, but not these 30-second attacks ads that I’ve just been deluged with,” he said.

In the end, King explained that all the attention he was getting was a sign his campaign was on track.

“One of my favorite sayings is: Yyou don’t take flak unless you’re over the target.”

The new NRSC ad, below, is part of a two-week, $600,000 buy:

youtube.com/watch?v=HbLqufRfEiU

Correction: 5:04 p.m.

An earlier version of this post had an incorrect reference to Portland. Portland is Maine’s largest city; Augusta is its capital.