NORRIDGEWOCK, Maine — U.S. Trade Representative Michael Froman stressed the importance of manufacturing jobs and strengthening the middle class as he spoke to hundreds of employees at a New Balance athletic shoe factory on Monday morning.

Froman toured the facility along with New Balance CEO Rob DeMartini, U.S. Rep. Mike Michaud, and U.S. Sen. Angus King. They spoke to New Balance associates about their work and why they believe it’s important to save American manufacturing jobs by keeping existing footwear tariffs in place.

Froman toured the Norridgewock plant that has nearly 400 employees. New Balance also has facilities in Massachusetts, Michigan and Missouri. Its Maine facilities in Norway, Skowhegan and Norridgewock consist of more than 900 workers.

“We’re asking the administration to do everything they can to focus on jobs in America, not jobs in Asia,” said DeMartini.

Froman is the U.S. ambassador helping negotiate the Trans Pacific Partnership, a free trade agreement being negotiated among countries in North America, Asia and Australia.

“I asked Ambassador Froman to come here for one simple reason, because I’m so damn proud of you and I wanted him to see that,” said King.

The agreement is “all about opening up Asian markets to our products,” King continued. “But also being sure that we’re careful about how we open up our market to their products. That’s really what this is all about. It’s all about Vietnam, quite frankly, and their desire to make more shoes there and their desire for us to make less shoes here.”

Maine lawmakers said they want to keep the tariffs in place that allow New Balance to stay competitive with Asian athletic footwear makers.

“My position is pretty simple. I don’t think that our companies should have to compete around the world with companies that don’t follow the rules that you have to follow here,” said King. “Whether they’re labor rules, hour rules, environmental rules, and it’s really not a question of free trade, but fair trade.”

“This is actually the most important and most sensitive issue in the negotiations,” said Froman.

The athletic footwear portions of the Trans Pacific Partnership negotiations will take place in late August in Brunei, he said. The partnership agreement should be signed this year, he added.

Member countries of the TPP are Australia, Brunei Darussalam, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore, the U.S. and Vietnam, according to the U.S. trade representative website. Malaysia and Japan are already Maine’s second and third largest export markets, the website states. Maine exports are growing twice as fast as the overall Maine economy and more than three times as fast as the U.S. economy as a whole, according to the website. More than 30,000 Mainers go to work every day because of exports, including 17 percent of all manufacturing workers in Maine. According to the website, 85 percent of Maine’s exporters, nearly 1,800 companies, are small and medium enterprises.

Sue Burns, who has worked for New Balance for 14 years, is a fourth-generation shoemaker, she said. She challenged Froman to make the same commitment Ron Kirk, Froman’s predecessor, made to New Balance’s workers last September when he visited. Kirk said the Obama administration would fight to keep their jobs in the U.S.

“I just want to be the face that haunts your decisions,” Burns said, receiving laughs from the crowd.

“I know you have a tough job. So do we,” she said. “If your job could be eliminated because of the decisions that we make here in Maine while you’re in Washington, you’re probably nervous about it too. [Could you] make the same pledge to make sure we will still have jobs when that decision’s made?”

Froman didn’t directly make the pledge, but said his goal is to maximize U.S. jobs.

“I will guarantee that we will take all of your thoughts and all of your concerns and make sure we are fully integrating them into our thinking,” Froman said. “We’re trying to strike a very good balance here in making sure people continue to produce here.”

Michaud said he agreed with President Barack Obama’s speech last week that stressed that the U.S. economy succeeds when the middle class succeeds.

“He highlighted the need for more manufacturing and the need to see more ‘Made in the USA’ again as a way to build the middle class,” Michaud said. “I believe that making sure New Balance continues to make footwear in the United States is a perfect example of how we can do just that.”

U.S. Sen. Susan Collins, R-Maine, was unable to make it to the factory on Monday. She prepared a statement saying she had to be on the Senate floor because of her position as Senior Republican on the Transportation and Housing Appropriations Subcommittee.

“Maine has a long, proud history of manufacturing,” she said in a statement. “I am confident that Ambassador Froman will leave here with a greater appreciation for the pride that Mainers have in their work and the contributions the footwear industry and every worker make to Maine’s economy.”