Canada is voting for its next leader. Here’s what to know.

Canadians on Monday will choose a prime minister to negotiate with President Trump over trade and security, and to navigate their economy through turbulence as businesses freeze spending and hiring.

Mark Carney, the Liberal prime minister and former central banker, has championed his experience navigating economies through tough times as Canada’s best chance to contain the damage from Trump trade policies. Conservative challenger Pierre Poilievre has also vowed to take a hard line with Trump, adding that Canadians can’t afford a fourth Liberal term after living standards declined during a decade under Carney’s predecessor, Justin Trudeau.

The winner will assume heightened expectations to protect the country and set it on an economic path less reliant on the U.S. Here’s what to know about Monday’s federal election:

What are the main campaign issues?

The candidates are focused on how to handle Trump and reorient an economy dependent on U.S. demand. After a March 28 phone call with Trump, Carney said the president agreed to start talks after the election on a new economic and security deal between the North American neighbors. Poilievre has pushed for a faster renegotiation of the U.S.-Mexico-Canada trade deal. Both candidates say they will boost military spending to allay U.S. criticism, but they have established lines that can’t be crossed in talks such as control of Canadian resources, changes to its language laws, agricultural policy and sovereignty.

Both the Liberals and Conservatives have pledged a combination of tax cuts and spending to help the economy after confidence among businesses and households has plummeted to historic lows. The Conservatives want deeper cuts to public-sector spending.

Poilievre made inroads with voters on affordability after years of high inflation and housing prices that are among the highest in the world. His focus on cost-of-living challenges after a decade of Liberal rule helped lift the Conservatives to a 20-point-plus lead in the polls before Trudeau’s departure and Trump’s trade moves.

Voters waiting to cast their ballots at an advance polling station in Vancouver earlier this month.

How do Canada’s elections work?

Canadians will vote Monday for local members of parliament, with most candidates running under a party banner. The party that wins the most local races forms the next government, and the party leader becomes prime minister.

Pollsters predict Trump’s volleys against Canada will draw one of the biggest election turnouts in decades. Turnout was 63% in 2021, compared with a recent peak of 75% in 1988, when debate over a U.S.-Canada free-trade deal drove the campaign.

Heavy turnout tends to benefit opposition parties because it suggests voters want change, said Kathy Brock, a politics professor at Queen’s University in Kingston, Ontario. This election is unique, she said, because it pits voters who want a new government after three Liberal terms against voters seeking stability amid uncertainty emanating from Washington.

What does polling suggest?

Recent polling points to one of the biggest turnarounds in Canadian political history. The Liberals are polling with a three-point lead over the Conservatives, 42% to 39%. In January, after Trudeau said he would step down, the Conservatives held a lead of more than 20 points. The gap narrowed after Trump took office and escalated his threats to Canada’s economy and sovereignty. The Liberals overtook the Conservatives around when Carney became prime minister in mid-March.

According to polling aggregator 338Canada, the Liberals hold solid leads in Ontario and Quebec, provinces bordering the U.S. and where about 60% of Canada’s voters reside. 338Canada, as of Friday, pegged the likelihood of a Liberal majority win at 68%.

When are the results expected to be announced?

Results will come after 9:30 p.m. ET, when voting stations close in most parts of the country. Voting stops in British Columbia on the Pacific Coast at 10 p.m. ET.

The number to watch is 172: the lawmakers a party needs to win a majority in Canada’s legislature. A majority means the governing party doesn’t need support from the opposition to pass legislation. The Liberals have led a minority government since 2019, which required cutting side deals with smaller parties to govern.

Write to Paul Vieira at Paul.Vieira@wsj.com