President Donald Trump on Monday marked election day in Canada by pushing his plan for the country give up its independence and become part of the United States.

Canada could become "the cherished 51st state," he said on social media. "No more artificially drawn line from many years ago. Look how beautiful this land mass would be."

"Free access with NO BORDER. ALL POSITIVES WITH NO NEGATIVES. IT WAS MEANT TO BE!" he wrote.

"America can no longer subsidize Canada with the Hundreds of Billions of Dollars a year that we have been spending in the past. It makes no sense unless Canada is a State!"

Canadians were voting Monday for a new government to confront the annexation threats from the United States and to deal with Trump's trade war that defined the election campaign.

The Liberal Party, led by new Prime Minister Mark Carney, looked set to lose to the Conservatives' Pierre Poilievre until Trump's threats sparked a reversal in poll forecasts.

Trump is not on the ballot but he nonetheless urged Canadian voters to "elect the man who has the strength and wisdom to cut your taxes in half, increase your military power, for free, to the highest level in the World."