One of the key proposals of the Coalition Avenir Québec, the party leading in the polls, is to cut the number of immigrants to 40,000 a year. The party would also require them to pass a language and values test.

After a difficult start to the campaign, leader François Legault has played up his proposal and cranked up the rhetoric around the importance of preserving Quebec identity.

Here's a closer look at his party's proposal and what it would it mean for the province.

What exactly is the CAQ proposing?

Legault has often equated the CAQ's target of 40,000 to a 20 per cent reduction in immigration levels. In fact, Quebec accepted 52,388 people in 2017, so meeting the target would mean the equivalent of a 24 per cent reduction.

The CAQ, a nationalist party that has taken a hard line on identity issues, wants immigrants to pass a values and language test to qualify for a Quebec selection certificate. Immigrants would also have to prove they have been looking for employment.

Experts have questioned whether the party's plan would be legal under Canadian law.

Legault said Thursday some older immigrants under the family reunification program would potentially be exempt.

Is this plan realistic?

It's not entirely clear. Legault said Wednesday that the reduction in immigration levels would be put in place immediately, for 2019.

However, Quebec doesn't have full control over who is allowed to come to the province.

It has the power to select 31,000 economic immigrants a year, but it also gets another 12,000 people annually under Canada's family reunification program, as well as 9,000 refugees.

Legault said that, ideally, the reduction would be the same (meaning more than 20 per cent) across all categories. But, as the CAQ leader acknowledged on Wednesday, because Quebec only has jurisdiction over economic immigration, limiting the number of immigrants in the other categories would require negotiations with the Trudeau government.

Don't we need more workers?

In short, yes. A booming economy and aging workforce have combined to keep the province's unemployment rate at near record lows for the past year. The labour shortage has even forced some businesses to reduce their hours or close altogether.

A report released last fall by the Institut du Québec, a public policy think tank, called for an increase in the number of immigrants to sustain economic growth.

The current birth rate of 1.7 children per woman, along with 50,000 new immigrants annually, would be "insufficient" to maintain the current labour pool, the report said.

Another study released this week by the Business Development Bank of Canada found that 37 per cent of Quebec entrepreneurs had difficulty hiring new employees in the past 12 months.

Why does the CAQ want to cut immigration?

Legault says the Liberal government's policy is a "failure," and more needs to be done to ensure immigrants can enter the job market before bringing in more.

He points out that the unemployment rate is 15 per cent among immigrants who have been here for five years or less — nearly 10 points higher than the general population.

He also says that, after 10 years, more than a quarter of all immigrants end up leaving the province.

"We do not want to keep too many people who do not accept our language, our values and to participate in the workforce," Legault said when he announced the plan earlier this year.

According to a 2017 Statistics Canada report, though, a majority of immigrants living in Quebec — 80.5 per cent — reported being able to conduct a conversation in French.

What are the other parties promising?

Like the CAQ, the Parti Québécois also wants to cut the number of immigrants but has said it would leave the final target for the auditor general to decide.

Legault's chief rival, Liberal Leader Philippe Couillard, has committed to maintaining the current level of immigration and putting more money into integration and French lessons to help newcomers enter the job market more quickly.

Cutting the number of immigrants, Couillard said on the campaign trail, would be a "massive error" and detrimental to the economy.

Quebec City Mayor Régis Labeaume also made a forceful plea early in the campaign for Quebec to bring in more immigrants, saying the capital region badly needs more workers.

When asked about Labeaume's comments, Legault said Thursday he would ensure immigrants are better distributed across the regions to meet labour needs.