As autoworkers and dairy farmers protest a huge potential trade deal they say will cost them jobs, CTV News has learned that the aerospace and medical device industries stand to benefit.

Canada has tentatively secured the elimination of tariffs on all aerospace exports, like planes and engines, and medical devices such as MRI machines and dental equipment, according to sources close to the Trans-Pacific Partnership (TPP) negotiations.

That’s in addition to the removal of tariffs on metals and minerals, petroleum products, potash, steel, chemicals, plastics and industrial machinery, which CTV reported Wednesday.

The TPP is currently being negotiated by representatives of 12 Pacific Rim countries, including Canada, Japan, the U.S. and Australia, who are meeting this week in Atlanta, Ga.

Unifor, a union that represents many Canadian autoworkers, is concerned that a rumoured easing of the “rules-of-origin requirements,” would allow countries like Japan to export vehicles to North America with fewer Canadian-made auto parts.

Unifor national president Jerry Dias said Canada’s auto industry will take a “real beating” if the TPP deal is inked and the union estimates that 26,000 Canadian auto sector jobs could be lost.

On Tuesday, dairy farmers staged a protest on Parliament Hill to draw attention to their worry that the deal could affect the “supply management” system, making it cheaper for foreign dairy producers like New Zealand to sell their products in Canada.

At a campaign stop in Iqaluit on Wednesday, NDP Leader Tom Mulcair said he’s “very worried” about what Prime Minister Stephen Harper is willing to put on the trade table.

“I would take to the table a strong position to defend our supply-management system in its entirety and anybody else who wants to talk about that, we’ll start talking about their subsidies. But Mr. Harper seems to only feel faint any time it comes to defending our system,” Mulcair said.

Meanwhile, at an event in Toronto, Finance Minister Joe Oliver reiterated the Conservative government’s pledge that Canada “will not sign on, unless the deal is good for Canadians.”

At an event in Surrey, B.C., Liberal Leader Justin Trudeau said Canadians need to know the government is negotiating in a way that is going to “enhance Canadian opportunities and growth, while protecting our interests.”

Mark Warner, a lawyer who specializes in international business and regulatory law, told CTV’s News Channel that the TPP deal could be a “win” for Canadian consumers of milk and cheese

Warner also said the Canadian auto sector’s decline in recent decades is due to “changes in the auto industry itself” and that arguing about the percentage of domestic auto parts in the rules-of-origin requirement doesn’t help.

“The question you have to ask is, well why didn’t the 60 per cent level in NAFTA save (the industry),” Warner said. “So clearly that’s not the issue.”

While the TPP negotiations could fall through like they did back in July, Warner believes that “there is a willingness to do a deal” this week, given that U.S. President Barack Obama has a narrow window to get the deal passed this fall in Congress before the 2016 presidential campaign gets underway in earnest.

“Canada will probably have to make some concessions, either on auto parts or on agriculture,” Warner said. “And depending on how much we’re prepared to give on one, will probably dictate how much we have to give on the other.”

With a report from CTV News Parliamentary Correspondent Richard Madan