US President Donald Trump's suggestion that Canada should become the 51st state of the United States has been met with defiance from Canadians.

Adam Chapnick, a professor at the Canadian Forces College, a school for military officers, said that Trump's remarks have led to a heightened level of national unity.

"This began as a bit of a joke and then evolved into being more of a troll," Chapnick told China Daily. "While the president might genuinely think that Canada and Canadians would fare better as the 51st state, without a direct US military attack on Canada, there is no likelihood whatsoever of this happening."

A poll in January by the Angus Reid Institute found that 90 percent of Canadians oppose joining the US, and 4 out of 5 people in the US say it should be up to Canada.

The poll also found that US citizens are twice as likely to oppose (49 percent) Canada joining their nation than supportive (25 percent).

White House press secretary Karoline Leavitt said on Wednesday that Trump "feels strongly that it would be very beneficial for the Canadian people to be the 51st state of the United States. They wouldn't be paying for these tariffs. They'd have much lower taxes if they were part of our country."

On Thursday, however, Trump said he would again pause tariffs until April 2 on imports from Canada and Mexico covered by the US-Mexico-Canada trade agreement, offering the countries yet another reprieve. Ottawa responded in kind by delaying its own reciprocal tariffs on the US.

Trump, who recently referred to Canadian Prime Minister Justin Trudeau as "governor", spoke via phone with him on Wednesday over the 25 percent tariffs imposed by the Trump administration last week.

Canadian Foreign Minister Melanie Joly has told the BBC that she takes Trump's remarks on making Canada the 51st state "very seriously".

"This is not a joke anymore," Joly told Newsnight. "We're insulted. We're mad. We're angry."

While some younger Canadians have expressed openness to closer ties with the US for economic reasons, Chapnick said he believes it does not represent a shift in public sentiment.

On how Canada should navigate its relationship with the US, Chapnick said: "Generally speaking, the way that we have. Speaking with a single voice (we have not been perfect on this), making clear that we do not want a trade war but that we will not be bullied."

Darrell Dorsk, owner of a glass-works store, said he believes Trump's 51st state remarks, while provocative, reflect certain economic realities that Canadians should not ignore.

"I don't think he's serious, but it's a provocative statement. The polls are saying that all the older Canadians are very much against this," Dorsk said. "Because of the trade imbalance, Canada derives a lot of benefit from being so close to the US."

Meanwhile, Canada's Liberal Party looked set on Sunday to choose its next leader.

Mark Carney, who served as the governor of the Bank of Canada and the Bank of England, is one of the top contenders for the Liberal leader's post when results from a vote of around 400,000 party members are to be announced later on Sunday.

The other main challenger is Trudeau's former deputy prime minister, Chrystia Freeland, who held several senior cabinet positions in the Liberal government that was first elected in 2015.

Whoever wins the vote will take over from Trudeau as prime minister, but will soon face a general election.

Agencies contributed to this story.

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