BANGOR, Maine — The U.S. Chamber of Commerce waded deeper into Maine’s U.S. Senate race Tuesday, hosting joint campaign appearances with Republican U.S. Senate candidate Charlie Summers at businesses in Bangor, Lewiston and Biddeford.

The campaign appearances came almost three weeks after the U.S. Chamber launched a $400,000 television ad campaign calling former Gov. Angus King the “king of spending” and the “king of mismanagement.” The U.S. Chamber had announced its endorsement of Summers just days before the ad began airing on Maine stations.

During a morning news conference at Bangor’s Quirk Auto Park car dealership, the U.S. Chamber’s political director, Rob Engstrom, repeated the ad’s talking points against King while championing Summers, Maine’s current secretary of state.

“We think voters here have a clear choice between the free enterprise system and more government solutions,” Engstrom said. “We need leaders in Washington who understand the private sector, who come from the private sector.”

Summers repeated his call for government to “get out of the way” of small business, saying Congress needs to repeal the Obama administration’s health care reform law, eliminate federal regulations that hamper businesses and create a federal small business advocate position, emulating a new small business advocate position in the Maine Secretary of State’s office.

“I want to get government out of the way, and there are those in this race who don’t,” said Summers.

Summers is a former New England regional administrator for the U.S. Small Business Administration, which counts advocacy for small businesses among its roles. But Summers campaign manager Lance Dutson said a federal small business advocate would focus more on helping businesses navigate the federal bureaucracy.

“The changes in the last couple of years in Maine have certainly opened people’s eyes to the fact you can do things in government that are helpful to business, and it doesn’t have to be an adversarial relationship,” Dutson said.

The U.S. Chamber is expected to spend tens of millions of dollars this election cycle on a number of key Senate races. In Ohio, for example, the Chamber already has recorded $914,000 in spending on an ad campaign attacking incumbent Democratic Sen. Sherrod Brown, and the organization — along with other conservative groups — plans to spend much more.

Engstrom on Tuesday called the Maine Senate race a “battleground” and a “top-tier race that’s going to decide the balance of power in the United States Senate.”

While there’s been no public polling in Maine’s Senate race since the U.S. Chamber launched its ad campaign, “it wouldn’t be surprising to learn the ad has had an impact,” said Dan Demeritt, a Republican political consultant and former communications director for Maine Gov. Paul LePage.

“They’re making a relatively small investment to see if they can move Angus’ numbers down and what messaging may or may not be working,” said Demeritt, who writes a political column for Maine Sunday Telegram. “Given how high Angus started, his numbers have nowhere to go but down, franky.”

The most recent public poll in the six-way Senate race, which also includes Democrat Cynthia Dill and independents Steve Woods, Andrew Ian Dodge and Danny Dalton placed King on top with 55 percent support. Summers had the support of 27 percent of those polled, and Dill placed third with 7 percent support.

King spokeswoman Crystal Canney said Tuesday the former governor’s campaign doesn’t “have any polling that would indicate there’s been an effect” from the U.S. Chamber ad.

“What we know for sure is, we’re getting tons of calls in our office from people who are upset by the U.S. Chamber’s ad,” she said.

King on Tuesday was touring Madison and Skowhegan, where he visited the New Balance shoe manufacturing facility and discussed U.S. trade policy. He disputed the notion that the federal government should back out of the way entirely as a way to help business.

“I certainly know what government should and shouldn’t do for business,” he said in a prepared statement from his campaign. “But there are cases like New Balance in Skowhegan where if government got out of the way entirely, we would lose those jobs and they would be shipped overseas.”