Pierre Poilievre loses his parliamentary seat, the CBC says.

Preliminary results were likely to be available overnight Tuesday. A minority government would require support from other parties to pass legislation and would be weaker and less stable than a majority.

But the voters’ decision sealed a stunning reversal for the Liberal Party that just months ago seemed all but certain to lose to the Conservative Party. Mr. Carney has been prime minister since March, when Prime Minister Justin Trudeau stepped down.

The centerpiece of Mr. Carney’s acceptance speech early Tuesday morning was Canada’s response to Mr. Trump’s policies.

“As I’ve been warning for months, America wants our land, our resources, our water,” he said. “President Trump is trying to break us so he can own us. That will never happen.” He warned Canadians that the road ahead would be difficult and might require sacrifices.

When Mr. Poilievre conceded early Tuesday morning, he said that he would remain as party leader. The Conservative caucus can remove him from the post, which it did to the party’s two previous leaders after it failed to form the government.

The election has been remarkable in many ways, with candidates and many voters describing it as the most important vote in their lifetimes.

It has been dominated by Mr. Trump and his relentless focus on Canada, America’s closest ally and trading partner. Mr. Trump has imposed tariffs on Canadian goods, pushing the country toward a recession, and repeatedly threatened to annex it as the 51st state. Even as Canadians were heading to the polls on Monday morning, he repeated that desire, arguing on social media that it would bring economic and military benefits.

Mr. Carney, 60, a seasoned economist and policymaker who promoted himself as the anti-Trump candidate and centered his campaign on dealing with the United States, ultimately benefited from the American president's actions.

Mr. Poilievre, 45, and the Conservatives had been dominating polls for years, building a platform against the Liberals and Mr. Trudeau around the argument that they had dragged Canada into prolonged economic malaise.

But they watched their double-digit lead rapidly evaporate after Mr. Trump’s aggressiveness toward Canada and Mr. Trudeau’s resignation.

Canadians heading to the polls were preoccupied both with the country’s relationship with its neighbor to the south and with the state of the economy at home. Affordability worries, primarily over housing, were top of mind, opinion surveys conducted before the election showed.

But Canada’s choice on Monday also came as a kind of referendum against Mr. Trump and the way he has been treating America’s allies and its trading partners.

It’s the second major international election since Mr. Trump came to power, after Germany, and Canada’s handling of the rupture in the relationship with the United States is being closely watched around the world.

The election also highlighted that Mr. Trump’s brand of conservative politics can turn toxic for conservatives elsewhere if they are seen as being too aligned with his ideological and rhetorical style. Mr. Poilievre, who railed against “radical woke ideology,” pledged to defund Canada’s national broadcaster and said he would cut foreign aid, seemed to have lost centrist voters, pre-election polls suggested.

For Mr. Carney, Monday’s victory marked an astonishing moment in his rapid rise in Canada’s political establishment since entering the race to replace Mr. Trudeau in January.

A political novice but policy-making veteran, Mr. Carney conveyed a measured, serious tone and defiance toward Mr. Trump’s aggressive overtures, helping to sway voters who had been contemplating supporting the Conservatives, according to polls and some individual voters. And his politics as a pragmatist and a centrist seemed to better align with Canada’s mood after a decade of Mr. Trudeau’s progressive agenda.

The road ahead for Mr. Carney and his new government will be hard. For starters, he will need to engage with Mr. Trump and his unpredictable attitude toward Canada and discuss fraught issues, including trade and security.

And he will need to show voters that his economic policy credentials can truly be put to use to improve Canada’s slow economic growth and persistently high unemployment.

Bruce Fanjoy, the Liberal candidate who is a well-known community volunteer but was initially considered a long shot, won the race.

Mr. Poilievre embraced some of Mr. Trump’s rhetoric, railing against “radical woke ideology” while pledging to defund Canada’s national broadcaster and cut foreign aid.

1. Ottawa

   Cole Burston for The New York Times

2. Ottawa

   Nasuna Stuart-Ulin for The New York Times

3. Ottawa

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4. Ottawa

   Nasuna Stuart-Ulin for The New York Times

5. Ottawa

   Cole Burston for The New York Times

6. Ottawa

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7. Yellowknife, Northwest Territories

   Pat Kane for The New York Times

8. OttawaStaffers setting up TD Place for the election night event for Prime Minister Mark Carney.

   Cole Burston for The New York Times

9. Mississauga, Ontario

   Ian Willms for The New York Times

10. Montreal

    Nasuna Stuart-Ulin for The New York Times

11. Ottawa

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    Cole Burston for The New York Times

13. OttawaPierre Poilievre, the Conservative seeking to become prime minister, and Anaida, his wife, voting.

    Andrej Ivanov/Getty Images

14. OttawaPrime Minister Mark Carney, and his wife, Diana,  arriving at a polling station.

    Cole Burston for The New York Times

15. Toronto

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16. Toronto

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17. Mississauga, Ontario

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18. Montreal

    Nasuna Stuart-Ulin for The New York Times

19. Dildo, Newfoundland

    Greg Locke/Reuters

The polling stations’ results are then reported to Elections Canada, which immediately releases them online.

Because the ballot boxes are not moved to central counting locations, the first results usually begin trickling in soon after the polls close. The full count tends to extend until well after the broad results of the election have become clear.

“That’s just not what this election is about,” said Jessica Green, a political scientist at the University of Toronto who focuses on climate issues.

What the election is about, nearly everyone agrees, is choosing a leader who can stand up to Donald J. Trump. The American president has been threatening Canada with a trade war, if not total annexation as the “51st state.”

Leading in the polls is the Liberals’ Mark Carney, who has a decades-long pedigree in climate policy. For five years, he was United Nations Special Envoy on Climate Action and Finance, and he spearheaded a coalition of banks that promised to stop adding carbon dioxide to the environment through their lending and investments by 2050.

Despite that résumé, Mr. Carney has not made climate central to his campaign. When Prime Minister Justin Trudeau stepped down, one of Mr. Carney’s first moves was to scrap one of his predecessor’s least popular policies, a tax on fuel that included gasoline at the pump and was based on emissions intensity.

Even though most Canadians got much of that money back in rebate checks, Mr. Carney called the policy poorly understood and thus “too divisive.”

That move, coupled with what many see as similarities between his Conservative Party opponent, Pierre Poilievre, and Mr. Trump, have helped Mr. Carney as he’s risen in the polls.

Mr. Carney, a former central banker and business executive, dealt with the Chinese establishment in his recent private-sector roles for companies with investments in China.

But what was once an asset — experience working with a rising global power — has become a political liability in Monday’s national elections.

Mr. Carney and the Liberals have come under criticism for supporting a parliamentary candidate with connections to groups representing China’s Communist Party in Canada. Foreign interference in diaspora communities in Canada by China, India and other nations has been a concern for both parties, and the subject of inquiries.

The relationship between Canada and China sharply deteriorated following a diplomatic crisis that began when Canada detained a Chinese executive in 2018 on behalf of the United States.

Days later, the Chinese authorities detained two Canadian men, holding them for two and a half years.

For many Canadians, the dispute underscored the ruthlessness of China’s Communist Party.

“If you take the pulse of Canadian society, most people would hold unfavorable views toward China,” said Lynette Ong, a Chinese politics professor at the University of Toronto. “It’s politically incorrect to say out loud that there is a need to work with China on certain issues.”

Of the various accusations leveled against Mr. Carney as he tries to lead his party to victory in Monday’s election, claims about his allegedly nefarious links to China have been the most persistent.

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.

An unapologetic MAGA-aligned conservative, she has riled Canadians across the country by speaking admiringly of President Trump and focusing on her province’s fortunes, particularly its oil exports, even as the U.S. administration menaces Canada.

Ms. Smith, 54, has been premier for the past two and a half years, having spent the past two decades dipping in and out of politics.

“I keep getting fired,” she chuckled in an interview with The New York Times in Calgary, Alberta, in February.

She has also worked as an economist, a lobbyist and a radio host of a popular call-in show in which she honed her folksy, affable, but sharply ideological raconteur style.

She’s the closest thing Canada’s conservative movement has to a MAGA ally — and has the Mar-a-Lago photograph with Mr. Trump to prove it.

As Mr. Trump started to say he wanted to make Canada the 51st state, before his inauguration, Ms. Smith visited him in Florida.

Even before Mr. Trump’s re-election, Ms. Smith had been key in shaping the evolution of Canada’s broader conservative movement. Critics say she has courted ideological minorities, including fervent anti-vaccine organizations, advocates for Albertan secessionism and hard-line anti-trans activists, to secure her election.

She has been careful to make those groups feel included in her agenda while not fully endorsing their rhetoric.

That ability, along with the political freedom afforded by her lack of interest in national office, has put her at the vanguard of Canada’s changing right.

In recent months, Ms. Smith has defended her pro-Trump overtures as a diplomatic approach that complements the more aggressive stance taken by the federal government.

Simply put, she said of her Trump ties, “I’m happy to be good cop.”

The country’s westernmost province, British Columbia, will close a half-hour later than Ontario and Quebec do, at 10 p.m. Eastern.

(Elections Canada, the nonpartisan agency that administers the federal election, has a complete list of polling hours.)

About 7.3 million Canadians cast their ballots during the early-voting period, April 18 to April 21, according to Elections Canada, a 25 percent increase over early-voting turnout in the 2021 election.

Many Bloc supporters came to the conclusion that the French language and Quebec’s culture would have a better chance of surviving inside Canada, not as part of a 51st American state. Bloc strongholds around the island of Montreal suddenly became battlegrounds.

In one such electoral district south of Montreal, La Prairie-Atateken, where the Bloc won comfortably in the past two elections, polls showed a dead heat. A longtime Bloc supporter, Yannick Maheu, 52, voted for the Bloc, along with his daughter, Rosaly, 20, who was voting for the first time. But he said he had also been drawn by Mark Carney as the best equipped to deal with Mr. Trump and was pleased that polls show the Liberals heading toward a victory.

“I wouldn’t have supported the Liberals if Justin Trudeau were still prime minister,” he said. “But with Carney, under the current circumstances, I think a Liberal government will be good for us.”

Christine Lussier, 55, and her husband, Raymond Thibert, 67, voted for the Liberal candidate. They were worried about the economy and said their retirement savings had taken a hit because of Mr. Trump’s erratic economic policies. “Mr. Carney is a businessman, and he can help Canada more than Mr. Poilievre, who was too much like Trump,” Ms. Lussier said.

Mr. Carney’s opponents included his chief contender, Pierre Poilievre, the leader of the Conservative Party, which for much of the past year had dominated polls and appeared headed for a certain victory in the April 28 federal election. Mr. Carney’s move into politics and Mr. Trump’s economic and political assault on Canada have since reversed the fortunes of the Conservatives, with the Liberals enjoying a slight lead in the polls.

The other candidates were Jagmeet Singh of the New Democratic Party and Yves-François Blanchet, the leader of the Bloc Québécois, a party that promotes Quebec’s independence and runs candidates only in that province.

The key takeaways from the two-hour debate: No one had concrete ideas on pushing back against Trump. The candidates were divided on crime. They argued over the funding of public broadcasting. They debated building oil and gas pipelines. And the Trudeau legacy hung over the debate.

All of the politicians agreed that President Trump’s economic policies and his proposal to annex Canada have created a crisis.

But none of them offered any specific details about how they would get the American leader to change course, beyond general talk of tough negotiations at which they would assert Canada’s sovereignty and economic independence.

“They want to break us so that they can own us,” Mr. Carney said.

Mr. Carney leaned on his past as the governor of the Bank of Canada during the 2008 economic crisis and his time as the governor of the Bank of England during Brexit to present himself as the ideal negotiator.

Mr. Poilievre, a lifelong politician, criticized the Liberal government of the last decade as putting Canada “under the thumb” of the United States.