BRUNSWICK — U.S. Senate candidate Angus King lambasted the U.S. Chamber of Commerce’s $400,000 ad campaign labeling him “king of spending” on Tuesday, saying he cut taxes, made prudent investments and eliminated budgetary “gimmicks” during his two terms as governor.

The political independent is irked by the ad’s claim that he was a free-spending chief executive who left the state with a “$1 billion budget shortfall” when he left office.

“It’s an easy potshot and it’s wrong,” he told The Associated Press.

The ad refers not to a budget deficit but to a theoretical budget gap that’s common before the governor and the Legislature set priorities, King said in an interview.

The ad overlooks his success in cutting the sales tax, providing property tax relief through the homestead exemption and giving incentives to job creation through the business equipment tax, as well as his work to eliminate budget “gimmicks,” invest excess cash in infrastructure and bolster the rainy day fund, King said.

“The real question is: The money came in. What did you do with it? It’s a fair question,” he said. “Fix gimmicks, cut taxes, make investments and put money in reserves.”

The Washington-based chamber has endorsed Republican Charlie Summers in the race.

Lance Dutson, Summers’ campaign manager, said the ads are factually correct and it’s ironic that King attacked former Democratic Gov. Joe Brennan for spending too much as governor when they faced off in the 1994 gubernatorial campaign.

“As governor himself, Angus made Brennan look like a pinchpenny,” Dutson said.

The U.S. Chamber ads, which began airing last week during NBC’s prime-time coverage of the Olympics, represent the first major negative advertising in the campaign for Republican Sen. Olympia Snowe’s seat.

The other candidates are Democrat Cynthia Dill and three independents: Steve Woods, Andrew Ian Dodge and Danny Dalton.

On Tuesday, King made his first direct remarks about the negative ads, which he predicted when he announced his candidacy.

The issue of the so-called structural gap is complicated, and it’s not easy to give a rebuttal in a 30-second time slot, King said.

State revenues were slowing down after the 9/11 attacks and end of the dot-com bubble, King said, but state spending was prudent and Mainers should know that there was never a deficit, which is barred by the state Constitution.

The chamber stood by the ad, saying it was accurate.

“Facts are stubborn things,” said Rob Engstrom, the chamber’s national political director.