Canadian Prime Minister Justin Trudeau will remain in power but with a minority government that will require the support of a smaller left-leaning party, official results showed after a hard-fought battle in which he was dogged by scandals.

Mr Trudeau’s Liberals had won or were leading in 156 out of 338 seats as of midnight EDT on Tuesday (3pm AEDT), according to Elections Canada.

That put the Liberals far short of the 170 seats needed for a second straight majority government.

Mr Trudeau, who took power in 2015 as a charismatic figure promising “sunny ways”, watched his popularity drop over old photos of him in blackface and his handling of a corporate corruption case.

He will now have to rely on the New Democratic Party to push through key legislation.

BREAKING NEWS: CBC News projects Liberal minority government. #Elxn43 #CanadaVotes #cdnpoli https://t.co/h0youyIvED pic.twitter.com/mDllEDirsr

— CBC News (@CBCNews) October 22, 2019

Although the NDP had a disappointing night, as the number of seats it was projected to win was down sharply from the 2015 election, the party could exercise significant influence over Mr Trudeau’s next government.

“I think a Liberal government supported by the NDP is likely going to lean farther left,” said John Manley, a former Liberal finance minister who now works in the private sector.

“It raises a series of issues about what are the demands that an NDP party would make. What’s the price of governing going to be? And I think businesses are going to be reluctant to make any moves until they get some satisfaction around that.”

Minority governments in Canada rarely last more than 2-1/2 years.

US President Donald Trump congratulated Mr Trudeau early on Tuesday, saying “Canada is well served”.

“Congratulations to Justin Trudeau on a wonderful and hard fought victory,” Mr Trump said on Twitter.

“I look forward to working with you toward the betterment of both of our countries!”

Polls had earlier showed a neck-and-neck race between Mr Trudeau and his main rival, Conservative leader Andrew Scheer.

The Conservatives, who trailed on Monday with 121 seats, actually held slightly more than a one percentage point lead in the popular vote over the Liberals.

Mr Trudeau, 47, who has championed diversity as PM, was endorsed by former US president Barack Obama in the final stretch of the campaign and is viewed as one of the last remaining progressive leaders among the world’s major democracies.

I was proud to work with Justin Trudeau as President. He's a hard-working, effective leader who takes on big issues like climate change. The world needs his progressive leadership now, and I hope our neighbors to the north support him for another term.

— Barack Obama (@BarackObama) October 16, 2019

But the son of the late Liberal prime minister Pierre Trudeau also had to overcome a sense of fatigue with his government.

Support for the Bloc Quebecois jumped in the mainly French-speaking province of Quebec, the only place where the separatist party contests elections. It was elected or ahead in 32 seats, more than three times what the party won in 2015.

“The Bloc Quebecois is surging in Quebec,” said Daniel Beland, director of the McGill Institute for the Study of Canada, who added that the election was a “clear defeat” for Scheer and the Conservatives.

The Greens, who have assailed Mr Trudeau for not doing enough to combat climate change, also made gains on Monday.

-AAP