Justin Trudeau's Liberal government is doing something no Canadian government has done for decades: It is gambling on a lot more immigration.

There should be no doubt that it is a gamble. On the day that U.S. President Donald Trump was responding to a terrorist attack in New York by blaming the immigration system, exploiting resentment there, the Liberals were saying Canada needs more immigrants. And don't think that's because it's a slam-dunk political winner with new Canadians: Polls show first-generation immigrants are not much keener on expanded immigration than those born here.

Mr. Trudeau's government is making a statement that it is going in a different direction. In fact, that's the statement that Immigration Minister Ahmed Hussen made. "We are emphatically and unapologetically taking the opposite approach," he said at a press conference in Toronto.

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The numbers that the Liberals are shooting for are nowhere near the massive, 450,000-a-year level proposed by the Liberal-appointed Advisory Council on Economic Growth headed by McKinsey and Co. guru Dominic Barton and backed by some big-business voices. Mr. Barton had suggested more newcomers could foster economic growth and mitigate the aging of Canadian society. But that would be a huge expansion, and for politicians, that's not just a gamble but going all in.

Yet Mr. Hussen's numbers are still large increases. Under Stephen Harper's Conservatives, there were typically about 260,000 immigrants each year. The Liberals have increased the target to 300,000 this year, and will keep increasing to 340,000 by 2020 – that's a 30-per-cent increase over a typical Conservative year, and a 21-per-cent increase over the Conservative 2010 high mark. When compared with the size of the population, the Liberals are planning a rate of immigration not seen since Brian Mulroney was in power.

Immigration levels dropped substantially for two years under Jean Chrétien, and levels have fluctuated from year to year, but no government since Mr. Mulroney's has made any sustained, substantive change to immigration rates – the number of immigrants as a percentage of the population. The Liberals plan to move the rate upward significantly.

It's a plan to keep increasing immigration steadily. Mr. Hussen even revived the Liberal target of increasing immigration to 1 per cent of the Canadian population – a promise made by Mr. Chrétien in 1993 but ignored once he was in power.

Politically, it's not the specific number that matters. The government has done polls that show that most Canadians don't have the foggiest notion how many immigrants come to Canada. But Canadians still have opinions on whether there are too many immigrants, or too few.

A survey commissioned in March by the Association for Canadian Studies found that 38.4 per cent of Canadians think there are too many immigrants, while just 10.4 per cent said there are too few. But a lot, 41.1 per cent, said that the number's about right. Perhaps that's one reason recent governments haven't risked changing things much.

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Jack Jedwab, the association's president, said the number of people who think there are too many immigrants is generally pretty stable, between 30 per cent and 40 per cent; it's near the high end of the range now. (The March survey was conducted by web panel that used a sample of 2,559 people.)

People born outside of Canada are a little less likely to think there's too much immigration, but not much. There is a substantial political divide: People who consider themselves on the right are far more likely to think there are too many immigrants than people on the left.

That may be one reason Mr. Trudeau's Liberals are willing to take a political gamble on immigration. It emphasizes a difference that plays better with left-leaning voters. And it represents a contrast with Mr. Trump. But it's still a gamble.

Even Mr. Trump is calling for a "merit-based" immigration system, which sounds similar to Canada's "high-skilled" class, rather than the United States's current visa lotteries. He won't end immigration; the Trump culture war is mostly about Mexicans and Muslims, and he has portrayed both as dangerous.

In Canada, Mr. Jedwab said, the resentment of immigration was once driven by economics – the sentiment that immigrants take Canadian jobs or cost the treasury – but now, it is clearly driven by perceived security concerns and fears immigrants are changing Canadian culture and values.

No wonder then, that Mr. Hussen emphasized the economic reasons for expanding immigration, noting, for example, that there will be fewer workers to support retirees in coming years. His plan also includes more family reunification, asylum-seekers and resettled refugees. People like the notion of hard-working economic immigrants, but not everyone is as positive about the rest. That's probably a very big reason why governments have not signalled a sustained change in immigration levels for a quarter century. Until now, they didn't want to take a risk.