Quebec's ruling Liberals, centrists but separate from the federal Liberal party, launched their campaign on Thursday. They trail in polls behind the center-right Coalition Avenir Quebec (CAQ).

In power for 13 out of the past 15 years, the Liberals hope to extend that run on the back of their economic track record, having balanced the budget and cut debt in the province.

The CAQ, led by Francois Legault, has said it too wants to reduce debt, but its vows to cut taxes, lower immigration, boost healthcare spending and bring in fresh blood may explain its edge in early polls.

The CAQ has also addressed fears by some voters of an erosion in Quebec's identity, with a promise to forbid people in positions of authority such as judges from wearing religious symbols like hijabs. Under the CAQ, immigrants would have three years to pass a French test to get the papers required in Quebec to become Canadian citizens.

Uncertainty over tariffs and the renegotiation of the North American Free Trade Agreement has taken center stage, with Quebec Premier Philippe Couillard arguing the Liberals will best protect the province's economy from the threat of the Trump administration's protectionist policies.

The Liberals announced C$863 million ($657 million) in aid just last week to mitigate the impact of U.S. tariffs on companies and the agriculture sector.

Quebec's aluminum sector has been hit directly by U.S. tariffs on metal imports from Canada and other nations, while U.S. President Donald Trump has directly attacked Canada's dairy industry, which is based largely in Quebec.

All major Quebec politicians support the dairy sector but farmers will be looking for "the candidate with the best plan to defend it," said François Dumontier, spokesman for les Producteurs de lait du Quebec, a dairy producers' group.

He did not elaborate. But the Quebec Liberal government's efforts have not gone far enough for Quebec pork and soy producers. Many fear becoming "collateral damage" amid slumping prices due to tariffs between the United States, China and Mexico, said Marcel Groleau, president of the Union des producteurs agricoles, a provincial trade union for agriculture.

"In the election campaign, it will be part of our demands to have a plan that will support our farmers during the uncertainty that exists," Groleau said in an interview.

According to Statistics Canada data for the week ending Aug. 11, Quebec hog prices declined 20 percent on an annual basis.

The Trump administration's $12 billion plan to aid American farmers hurt by tariffs has stepped up pressure on other governments to back their industries, Groleau said.

"The competition is not between producers, it's between governments," he said.

(Reporting By Allison Lampert in Montreal. Additional reporting by Rod Nickel in Winnipeg; Editing by Tom Brown)

By Allison Lampert