Canadian Prime Minister Justin Trudeau has announced he will step down in the coming months after nine years in power, bowing to pressure from lawmakers alarmed by his Liberal Party's miserable showing in pre-election polls.

A subdued Trudeau, among the most prominent progressive leaders in the world, told a press conference that he would stay on both as prime minister and Liberal leader until the party chooses a new chief within months.

"This country deserves a real choice in the next election, and it has become clear to me that if I'm having to fight internal battles, I cannot be the best option in that election," Trudeau said.

He also announced parliament would be prorogued, or suspended, until March 24.

That means an election is unlikely before May at the earliest, so Trudeau will remain in charge – at least initially – of dealing with the threat of crippling tariffs once US President-elect Donald Trump takes office on January 20.

The next election must be held by late October and polls show voters angry over high prices and a shortage of affordable housing will elect the opposition Conservatives and hand the Liberals a resounding defeat, no matter who leads the party.

In recent weeks unhappy Liberal lawmakers openly called on Trudeau to quit after his finance minister resigned and accused him of "political gimmicks" to win back voters.

"I am not someone who backs away from a fight, particularly when a fight is as important as this one is," Trudeau told reporters outside his residence.

"But I have always been driven by my love for Canada.

"It has become obvious to me with the internal battles that I cannot be the one to carry the Liberal standard into the next election."

Trudeau, 53, took office in November 2015 with a message of hope and "sunny ways" and won reelection twice, becoming one of Canada's longest-serving prime ministers.

But his popularity started dipping two years ago as prices of groceries and housing rose in the post-Covid period, and his fortunes never recovered.

Parliament was originally due to resume on January 27 and opposition parties had vowed to bring down Trudeau's minority government as soon as they could. But with parliament returning only on March 24, the earliest they could present a non-confidence motion would be some time in May.

Trudeau said he had asked the Liberal Party to set in motion a leadership contest but did not say how long it would take. A new party leader would become prime minister immediately, and lead the Liberals into the next election.

Shachi Kurl, president of pollster Angus Reid, said that while a new leader might be able to stem losses, the Liberal party was still in trouble.

"There is a fatigue factor. This is a government in its 10th year – at some point the milk just expires," Kurl said. "I think the milk has turned pretty sour."

Although proroguing parliament would allow the Liberals to choose a leader without worrying about an election derailing the process, the move could still hurt them with voters, said Philippe Lagasse, an associate professor and constitutional expert at Ottawa's Carleton University.

"People are ready for an election. They want to move on – this is just delaying it," he said.

Liberal infighting has alarmed business groups and the premiers of the country's 10 provinces, who say Ottawa has to focus on possible tariffs from the Trump administration.

"Canada needs to demonstrate stability and strength at this critical moment, and the federal government must urgently explain to Canadians how they will avoid tariffs that could have devastating effects," said Doug Ford, premier of Ontario, the most populous province.

Trudeau had until recently been able to fend off Liberal legislators worried about the poor showing in polls and the loss of safe seats in two special elections last year.

Ontario premier Doug Ford says Trudeau needs to focus on the tariff issue with his time left in office. - Reuters

But calls for him to step aside soared since last month, when he tried to demote Finance Minister Chrystia Freeland, one of his closest cabinet allies, after she pushed back against his proposals for more spending.

Freeland quit instead and penned a letter accusing Trudeau of "political gimmicks" rather than focusing on what was best for the country.

Freeland and former central banker Mark Carney, two potential candidates in the race to replace Trudeau, both issued short statements thanking him for his service.

Chrystia Freeland is a potential candidate in the race to replace Trudeau. – Reuters

The Conservatives are led by Pierre Poilievre, a career politician who rose to prominence in early 2022 when he supported truck drivers who took over the centre of Ottawa as part of a protest against Covid-19 vaccine mandates.

"While leaderless Liberals focus on saving their jobs and fighting each other for power, the country spirals out of control," Poilievre said in a statement, reiterating calls for an immediate election.

Trump, speaking before Trudeau's announcement, said he was looking forward to working with Poilievre if he won the next Canadian election.

"It would be very good. Our views would be more aligned, certainly," Trump said.

Conservative Party leader Pierre Poilievre has called for an immediate election. – Reuters

Alberta Premier, Danielle Smith - a Conservative - described Trudeau as "a lame duck leader with no immediate plans to leave", and announced her intention to attend Trump's inauguration in Washington, DC.

"Whatever internal dynamics the Liberal Party has to go through to, to get to that point is kind of up to them," she said.

"But I would have preferred today to see an election call, because I don't think two months delay is going to make any bit of difference to how Canadians are looking at this administration."

Alberta Premier Danielle Smith says Trudeau should have called an election instead of leaving the leadership of Canada in limbo. - Reuters

What happens now that Trudeau is resigning as Canada's PM?

Will Trudeau leave office immediately?

No. Trudeau will stay on both as prime minister and head of the ruling Liberal Party for now. Unlike the process in other countries such as Australia, where party leaders are elected by legislators and can be removed overnight, in Canada they are chosen by special leadership conventions that can take months to organise.

Will an election be held in the immediate future?

No. Trudeau announced that parliament – which had been due to resume work on January 27 – would instead be prorogued, or suspended, until March 24.

This means opposition parties who had originally planned to unveil non-confidence motions to bring his minority government down as soon as they could after January 27 will now have to wait until some time in May since the government controls the agenda for most of each session. If all the opposition parties vote together on the motion, the Liberals will be defeated and a new election called.

As a result, a new election is unlikely to be held before May at the earliest.

When parliament resumes, the government has to formally unveil its plans for the new session in the so-called Speech from the Throne. The Liberals are not obliged to make this subject to a vote of no confidence.

Parliament is scheduled to start its summer break no later than June 20 and if the Liberals are still in power by then, an election would be held as scheduled at the end of October.

How else could the Liberals be removed from power?

Under the original parliamentary calendar, the House of Commons elected chamber had been due to vote on spending measures in late March. This would trigger a confidence vote.

It is unclear whether that vote would still be scheduled for late March and if it were, whether the opposition parties would vote to bring down the Liberals, whether they are led by Trudeau or a new party head. The Conservatives, who are favoured to win the next election, and the left-leaning, small New Democratic Party have both made clear they want to defeat Trudeau on a formal motion of no-confidence that they themselves have presented.

The Liberals could also be brought down over their annual budget, which would most likely be unveiled in April. The initial vote on the legislation implementing the budget would be a matter of confidence but the government has some flexibility as to when that would take place.

Public policy professor Kathy Brock reflects on Justin Trudeau's resignation. – Reuters

How long does the party have to choose a new leader?

The nightmare Liberal scenario is that the party takes so long to choose a new leader that it has to fight the next election with Trudeau still in charge. It is likely therefore to announce a shortened contest designed to ensure that Trudeau's replacement is in office as soon as possible.

When Trudeau won the Liberal leadership in April 2013, the contest lasted exactly five months. In 2006, it lasted almost eight months.

Trudeau said he had asked the party to start the process of choosing a new leader. Liberal president Sachit Mehra said he would call a meeting of the party's national board this week to begin the process. He gave no further details.

Would a new leader help the Liberals avoid defeat?

Polls strongly indicate that the Liberals will lose the election, no matter who the leader is. But the scale of the defeat could be tempered if Trudeau is not in charge.

Who might run to replace Trudeau as Liberal leader?

The prospect of an election mauling might deter some candidates, especially if the party is crushed and ends up a shadow of its current self. Those who could run include Innovation Minister Francois-Philippe Champagne, Transport Minister Anita Anand, Foreign Minister Melanie Joly as well as former finance minister Chrystia Freeland and Mark Carney, former governor of the Bank of Canada and the Bank of England. Tradition dictates that Carney, currently Chair of Brookfield Asset Management, would need to secure a seat in parliament in order to take office if he won the party leadership.

Is there any other way Trudeau could be forced out?

Ultimate constitutional power in Canada lies with Governor General Mary Simon, who is the personal representative of Britain's King Charles, the head of state. She can in theory remove Trudeau, but there is virtually no chance of that happening.

"The governor general won't dismiss a prime minister who still holds the confidence of the Commons," said Philippe Lagasse, a professor and constitutional expert at Ottawa's Carleton University.