Live Updates: First Polls Close in Canada as Voters Choose Leader for Tumultuous Moment

But when those newcomers arrived and settled mostly in dense, urban areas, Canadians blamed the rising immigration levels for growing pressure on housing costs and social services like health care.

As Mr. Trudeau’s popularity dropped, his unpopular policy to accelerate immigration was dramatically undone. Several ministers announced their resignations when it appeared that Mr. Trudeau and the Liberals could not recover from the political damage of policies that included immigration.

As Canada rolled back its pathways for newcomers, Marc Miller, the last immigration minister under Mr. Trudeau, also linked societal strains to the number of newcomers in explaining the government’s decisions to scale back admissions.

The moment represented a sharp change in tone for Canada.

“For the longest time, immigration had always been lauded as a net benefit to the Canadian economy,” said Antje Ellermann, a director at the Center for Migration Studies at the University of British Columbia. “That really was a mantra, and policymakers were very careful not to talk about any potential costs of immigration.”

Then somewhat overnight, after Mr. Trump began to amplify his threats to Canada’s economy, the issue of immigration — which had partially caused the Liberals’ downfall — faded into the background.

“If it hadn’t been for Trump, we would see immigration as a quite salient issue in this campaign,” Ms. Ellermann said.

Polls have shown that Canadians think the country is accepting more immigrants than it should, an attitude that has prevailed, even among many of the newcomers.

“A lot of immigrants in Canada also feel there are too many immigrants,” said Jack Jedwab, chief executive of the Association for Canada Studies, a research group, and the Metropolis Institute, a think tank focused on migration.

Mr. Jedwab’s recent analysis, based on surveys conducted by the firm Leger, showed higher support for Liberals among immigrants whose first language is neither English nor French. But that is a small minority in Canada.

“Our demographics have evolved so much that it’s hard to really refer to an ‘immigrant vote,’” said Mr. Jedwab, adding that immigrants tend to vote based on regional trends.

As much is clear in Brampton, Ontario, a suburban city west of Toronto where more than half of residents are South Asian. Conservative leader Pierre Poilievre focused an April 9 campaign rally on crime control, knowing the city’s residents faced rampant home invasions, car thefts and extortion rackets that targeted immigrants.