Canadian Prime Minister Justin Trudeau announced on Monday that he will step down as leader of the ruling Liberals after nine years in office but will stay on in his post until the party chooses a replacement.

Trudeau, under heavy pressure from Liberal legislators to quit amid polls showing the party will be crushed at the next election, said at a news conference that parliament would be suspended until March 24.

That means Trudeau will still be prime minister on January 20 when US President-elect Donald Trump takes office. Trump has threatened to impose tariffs that would cripple Canada's economy.

"I intend to resign as party leader as prime minister after the party selects its next leader through a robust, nationwide competitive process," Trudeau said. "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, 53, took office in November 2015 and won re-election twice, becoming one of Canada's longest-serving prime ministers.

But his popularity started dipping two years ago amid public anger over high prices and a housing shortage, and his fortunes never recovered.

Parliament was due to resume on January 27 and opposition parties had vowed to bring down the government as soon as they could, most likely at the end of March. But if parliament does not return until March 24, the earliest they could present a non-confidence motion would be some time in May.

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.

But calls for him to step aside have 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. (Reuters)