Canadians head to the polls on Monday for a consequential election that could define the ongoing relationship against a backdrop of fraught relations with the US government.

The return of US President Donald Trump has shaken Canadian politics, potentially swinging what was looking like a likely return to power for the Conservative Party at the start of the year into a toss-up with the incumbent Liberal Party.

With polls tightening, there remains the possibility that no one party will get the majority required to govern outright, which will mean smaller parties will be courted to provide "supply and confidence" — a guarantee to support budget measures and back the government in confidence votes.  

Whatever Canadians decide, the next government will need to chart a challenging course, amid tensions with the United States as well as a difficult social and economic picture at home.

Here's what you need to know ahead of Monday's vote:

Canadian elections: 343 seats up for grabs

Canada is a parliamentary democracy, part of the Commonwealth of Nations, and draws many of its political institutions and conventions from the United Kingdom.

Its head of state is the UK monarch Charles III, who is represented by a governor general, currently Mary Simon.

The country has two houses of parliament: An appointed Senate, which is similar to Britain's House of Lords, and a voter-elected House of Commons. 

This federal election will see 343 members elected to the Commons, which is modelled on the UK's "Westminster" parliament, and where the new government is formed.

Canada's contenders: Liberals, Conservatives and more

The governing Liberal Party is led by Prime Minister Mark Carney, only the second person to hold the prime ministership without having been elected to the Commons.

The 60-year-old ascended to the role in March after resoundingly winning 86% of registered party member votes following the resignation of former PM Justin Trudeau.

Carney is an economist and former governor of both the Bank of Canada and the Bank of England. He will run for election to the Commons in the electoral district of Nepean, in Ottawa.

The other major group is the Conservative Party, led by Pierre Poilievre. Under his leadership, the Conservatives have won several by-elections, including taking two seats from the Liberals. He considers himself a "true conservative" with a small-government platform.

Other groups include the center-left New Democratic Party, the Quebec-centric Bloc Québécois, and the Green Party.

How voting works

A record 7.3 million people — roughly a quarter of Canada's 28.9 million eligible voters — have cast early ballots. Those who haven't can do so on Monday's official election day.

Canada, like the UK, uses a "first past the post" voting system to elect members of parliament. So in each electorate, the candidate who receives the most votes wins the seat.

Once the 343 members are elected to the Commons, the parliamentary group that can form a majority will become the nation's government.

While a single party can often form a government in its own right, a minority government will sometimes be negotiated if no party wins the necessary 172 seats. This has been the case for the last two Trudeau governments.

Rowdy neighbors shake up Canadian politics

Canada faces similar challenges to many nations around the world — a sluggish economy, rising unemployment, high prices, and a lack of access to quality housing. 

Like other incumbent governments elsewhere, the Liberal Party had been staring down the barrel of an electoral defeat this year.

Then Donald Trump returned to the White House and began to agitate Canadians with his brash political rhetoric.

Two of Trump's actions riled Canadians in particular: Remarks about annexing their country and incorporating it into the US as a "51st state" and starting a tariff war, with 25% duties imposed on most of Canada's exports crossing the border. 

It led to "elbows up" protests across Canada as well as calls to boycott US-made goods.

Trump's actions, the Canadian government's response to them, and a surge in Canadian nationalism are credited with energizing the election race.

A wild change in momentum amid Trump presidency

After taking the leadership of the Conservatives in September 2022, Pierre Poilievre's "straight-talking" confrontational style, borrowing from the Trump playbook, took the challenge to Trudeau.

And it looked to be paying off: Poilievre's Conservatives soared to a comfortable lead in opinion polls that grew to nearly double that of the Liberals by early January 2025, according to CBC News' poll aggregator.

Just as attacking the incumbent worked for Poilievre, so did resistance to Trump for the Liberals. 

Following Trump's inauguration, Liberal popularity has surged, from 20% at the start of the year, to 44% at the start of April. 

As of Saturday, the Liberals lead the Conservatives 42.5% to 37.8%, according to CBC.

While the race has tightened, CBC is also predicting a 74% chance the Liberals win an outright majority and just 1% chance the Conservatives would achieve the same outcome.  

Edited by: Ben Knight