Open this photo in gallery Coalition Avenir du Quebec leader Francois Legault greets supporters while campaigning September 7, 2018 in Montreal. Ryan Remiorz/THE CANADIAN PRESS

The Quebec election campaign resembled one that might take place in any other province for the first 14 days. Voters were treated to a large menu of small promises, minor scandals exposing disreputable candidates and acrimony over minor differences.

Then came François Legault’s pivot to identity politics on Day 15.

In an era of a dormant independence debate, the leader of the conservative Coalition Avenir Québec ended the week turning the spotlight on two issues that still set Quebec apart: immigration and the French language. The front-runner for the Oct. 1 vote then combined the two and touched raw nerves as he explained his plan to cut Quebec’s immigration quotas – a power held by no other province – is intended to protect the French language.

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“It’s the responsibility of the Premier of Quebec to protect the nation, to protect the French language in Quebec,” Mr. Legault said. “The risk is that our grandchildren won’t speak French. Quebec, in North America, surrounded by hundreds of millions of anglophones, will always be vulnerable.”

Mr. Legault’s immigration policy is long-standing: He wants to cut quotas for new arrivals, test those who do come for French language and adherence to Quebec values after three years and then expel those who don’t pass – a power the province does not have.

What’s new is the rhetoric. Until now he has framed the policy as a way to boost economic integration rather than a way to protect francophone culture from the existential threat of immigration.

Quebec is facing a stark labour shortage and Liberal Leader Philippe Couillard, who favours maintaining current immigration levels, had also framed the issue around economics.

“We need more workers in Quebec, including workers that come from elsewhere,” Mr. Couillard said. “It is a grave economic error to reduce those levels, one of the biggest economic errors we’ve seen in recent years from a political party.”

Mr. Legault’s policy is to cut Quebec’s immigration quota to 40,000, down nearly a quarter from the 52,388 people the province accepted in 2017.

The shift toward the immigration debate began Wednesday in a gigantic greenhouse operation southwest of Montreal. Mr. Legault toured row after row of towering cucumber plants carefully tended by a staff of 250 workers that includes about 180 temporary foreign workers from Central America. While the low-paid temporary workers are a federal responsibility and aren’t part of Mr. Legault’s plan, they inspired reporters to start asking him about immigration, and he started adding details to the plan.

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Quebec sets the overall immigration target of 50,000 but only selects the 30,000 economic migrants among them. The others, who are refugees and family unification cases, are selected by Ottawa. Mr. Legault said he would like to reduce numbers in all three categories but that would require considerable co-operation from the federal government.

The Trudeau government has shown no interest in either expelling immigrants who don’t learn French or cutting back in refugee or family reunification cases. “If a lot of Quebecers vote for the CAQ, Mr. Trudeau will have to take it into account or face the consequences in his own election,” Mr. Legault said.

Mr. Couillard accused the CAQ leader of threatening to break up immigrant families. “So if the kids learn the French language but dad doesn’t, we’ll send him away? What vision of society is this?”

Parti Québécois Leader Jean-François Lisée, running third and well out of contention, dismissed the “numerology” of the two leading parties, saying his party would select immigrants who speak French and avoid the debate over quotas. But by Friday afternoon he too was naming his immigration target: 35,000 to 40,000.

With the CAQ leading in most polls for the past year and all three main parties making promises to improve the education, health and elder-care systems, the election campaign had largely concentrated on whether Mr. Legault and his six-year-old party are ready to lead.

Mr. Legault’s campaign has been racked with distractions, often centring on the vetting of his hand-picked candidates. Stéphane Le Bouyonnec, one of the CAQ’s economic stars, resigned amid controversy over his loan business that charges interest ranging from 90 to 780 per cent – rates that are illegal in Quebec. The provincial ethics watchdog informed Éric Caire, an incumbent, that he was in potential conflict of interest over a $55,000 loan he took from a mayor in his riding.

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Stéphane Laroche, picked by Mr. Legault because of his community work with youth, resigned after revelations the province had sanctioned his bar in Saint-Jean-sur-Richelieu for serving minors and paying female employees less than men. His bar also held an annual event featuring a little person for entertainment. This was explained away by a party spokesman who said “the dwarf was well-treated and well-paid.” The candidate resigned.

Mr. Legault said he was unhappy with the spokesman but he remains with the campaign.