Washington DC - President-elect Donald Trump said Wednesday it would be "a great idea" for Canada to become the 51st US state, teasing on social media that "many Canadians" welcome the idea, as Ottawa is wracked by a political crisis.

"Many Canadians want Canada to become the 51st State," Trump posted on Truth Social.

"They would save massively on taxes and military protection. I think it is a great idea. 51st State!!!" he added.

The post is not the first time Trump has publicly mused at the idea, a joke that some have found in bad taste, particularly following the shock resignation of Canada's deputy prime minister on Monday.

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A public opinion survey by market researcher Leger this week nonetheless found that 13% of Canadians support the notion of linking up with their southern neighbor.

When Trump made the same comment to Canadian Prime Minister Justin Trudeau at a dinner at his Mar-a-Lago estate in Florida in late November, howls of laughter reportedly erupted.

According to conservative broadcaster Fox News, Trump suggested that merging the two nations would not only resolve his concerns about fentanyl trafficking, over which he has threatened a 25% tariff on Canadian goods, but could also stem undocumented immigration – a problem concentrated on the US southern border.

His suggestion raised eyebrows in Ottawa, with some commenting that it was "not funny," humiliating, and a not-so-subtle threat on the part of the incoming US leader.

Since then, Trump has repeatedly referred to Trudeau in social media posts as the governor of Canada.

The jabs have become more worrying for Canadians since the surprise resignation of Deputy Prime Minister Chrystia Freeland plunged the nation into a political crisis earlier this week.

She said in her resignation letter that she and Trudeau had locked horns over how to respond to Trump's tariff threats and manage a looming trade war with the US.

More than 75% of Canadian exports go to the US and nearly two million Canadian jobs depend on trade.

Freeland's move marked the first open dissent against an already weakened Trudeau from within his cabinet and has emboldened his critics.