Canada's ambassador to the U.S., Gary Doer, returned to Winnipeg on Monday to talk about his efforts to curb the "Buy American" trade policy. (Fred Chartrand/Canadian Press)

Former premier Gary Doer has returned to Manitoba to give his first speech in his home province as Canada's new ambassador to the U.S.

Doer told an audience of 750 at a chamber of commerce event in Winnipeg on Monday that his greatest challenge in Washington is the "Buy American" protectionist policy.

He said the policy might be politically popular, but trade barriers between Canada and the U.S. will do more harm than good. Doer said it's important that Buy American ideals don't lead to the U.S. becoming "Closed America" when it comes to trade.

"My view is it's a lot of work. It's very important to tie it back to where congressional people ... come from and what jobs in their district are tied to Canada, and that's the only way to make the case," Doer said.

"If we close our trade relationship even a little bit, it will hurt both of us."

Doer said he plans to travel to communities across the U.S. to talk about how protectionism will cost jobs.

He's also counting on a grassroots effort to maintain the open trade relationship Canada has with the United States.

He said Americans might have other issues on their minds right now, but the economy is still tops for legislators.