Canada's new Prime Minister Mark Carney on Sunday called early elections for 28 April, pledging to defeat Donald Trump's drive to annex the United States's huge northern neighbor.

Carney, a former central banker, was chosen by Canada's centrist Liberal Party to replace Justin Trudeau as prime minister, but he has never faced the country's broader electorate.

That will now change as Carney brought parliamentary elections forward several months from October, and he made it clear that the barrage of threats coming from the US president and the trade war he has launched will be the crux of his campaign.

"I've just requested that the governor general dissolve parliament and call an election for April 28. She has agreed," Carney said in a speech to the nation, referring to King Charles III's representative in Canada, a member of the British Commonwealth.

Trump "wants to break us, so America can own us. We will not let that happen," Carney said.

"We are facing the most significant crisis of our lifetimes because of President Trump's unjustified trade actions and his threats to our sovereignty," Carney said.

"Our response must be to build a strong economy and a more secure Canada."

In power for a decade, the Liberal government had slid into deep unpopularity, but Carney will be hoping to ride a wave of Canadian patriotism to a new majority.

Trump has riled his northern neighbor by repeatedly dismissing its sovereignty and borders as artificial, and urging it to join the United States as the 51st state.

The ominous remarks have been accompanied by Trump's swirling trade war, with the imposition of tariffs on imports from Canada, which could severely damage its economy.

"In this time of crisis, the government needs a strong and clear mandate," Carney told supporters on Thursday in a speech in the western city of Edmonton.

Poll favorites

Domestic issues such as the cost of living and immigration usually dominate Canadian elections, but this time around, one key topic tops the list: who can best handle Trump.

The president's open hostility toward his northern neighbor — a NATO ally and historically one of his country's closest partners — has upended the Canadian political landscape.

Trudeau, who had been in power since 2015, was deeply unpopular when he announced he was stepping down, with Pierre Poilievre's Conservatives seen as election favorites just weeks ago.

But the polls have narrowed spectacularly in Carney's favor since he took over the Liberals, and now analysts are calling this race, overshadowed by Trump, too close to call.

"Many consider this to be an existential election, unprecedented," Felix Mathieu, a political scientist at the University of Winnipeg, told AFP.

"It is impossible at this stage to make predictions, but this will be a closely watched election with a voter turnout that should be on the rise."

Poilievre, 45, is a career politician, first elected when he was only 25. A veteran tough-talking campaigner, he has sometimes been tagged as a libertarian and a populist.

Carney, 60, has spent his career outside of electoral politics. He spent more than a decade at Goldman Sachs and went on to lead Canada's central bank, and then the Bank of England.

Smaller opposition parties could suffer if Canadians seek to give a large mandate to one of the big two, to strengthen their hand against Trump.

As for the US leader, he professes not to care, while pushing ahead with plans to further strengthen tariffs against Canada and other major trading partners on April 2.

"I don't care who wins up there," Trump said this week. 

"But just a little while ago, before I got involved and totally changed the election, which I don't care about [...] the Conservative was leading by 35 points."