On the eve of crucial talks aimed at sealing a massive Pacific Rim trade deal, Conservative Leader Stephen Harper promised to protect Canada's dairy industry and insisted any decisions around supply management would be made by Canadians, not "foreigners."

During a campaign event in Vaughan, Ont., Harper stressed that any trade agreement must benefit Canada's "entire" economy and hailed the agricultural sector as the economic cornerstone to many local communities.

"This government remains absolutely committed to making sure we preserve our system of supply management through trade negotiations," he said. "Decisions to be made on whether we have such a system or not are decisions we want Canadians to take, not foreigners to take."

Canada's supply management system protects the domestic industry by controlling the price of milk, cheese, eggs and poultry through marketing boards and limiting imports through high tariffs.

Conservative Leader Stephen Harper is promising to protect Canada's dairy industry and says any international trade deal must be a benefit to the entire economy. (CBC)

Tomorrow, International Trade Minister Ed Fast will join the Canadian delegation in Atlanta for two days of talks on the Trans-Pacific Partnership (TPP). Conservatives hope to close the deal that would establish the world's biggest free-trade zone just weeks before the Oct. 19 federal election.

'Privileged access' to world markets

Harper said jobs of the future depend on Canada's "privileged access" to world markets. Touting the Conservative trade record, he accused his opponents of wanting to give up when the going gets tough in complex negotiations.

"Unlike the other parties, we're not going to walk away from a trade negotiation at the first sign of worry. We're there to make sure Canada is a full participant in the global economy of the 21st century," he said. "That's the only way we can create jobs, and we're the only party that has a record of doing it."

CBC News reported Friday that Canadian negotiators are prepared to concede a share of Canada's domestic dairy market to reach an agreement. American negotiators have demanded 10 per cent access to Canada's dairy markets under the TPP, but Canada rejected that proposal during talks in Hawaii in July.

Farmers brought placards, cattle and tractors to Parliament Hill Tuesday to protest any changes that could harm their industry.

Quebec dairy farmer Rene Buhlmann takes part in a protest Tuesday on Parliament Hill over possible concessions in the Trans-Pacific Partnership trade negotiations. (CBC)

Quebec dairy farmer Rene Buhlmann has supported the Conservatives in past elections, but said trade concessions that affect his industry could sway his vote.

"We have good regulations. We have good quality milk here in Canada. Why should we have any kind of milk coming in? Why can we not produce the milk here and sell it to our customers?" he asked.

Secrecy around deal

Liberal Leader Justin Trudeau accused Harper of negotiating a deal in "secrecy" and said a Liberal government would be more transparent about what's on the table. Canada must only agree to a deal that boosts jobs and protects farms, he said.

"We expect our Canadian government to continue to be able to do what governments of all stripes, including Liberal governments, have done in the past, in negotiating significant free trade deals without having to endanger the systems that work right now to protect our farmers."

Harper also said any TPP deal would not come at a cost to Canada's auto sector.

"We will only sign a deal if we believe it's in the best interests of all of our Canadian economy, including our auto industry."