More than 40 years ago, no less than the most powerful man on the planet predicted the younger Trudeau's destiny.

"Tonight we'll dispense with the formalities. I'd like to toast the future prime minister of Canada: to Justin Pierre Trudeau," Richard Nixon said during a state dinner in Ottawa hosted by Pierre Trudeau in 1972.

Justin Trudeau was four months old that day, the first born of a dashing prime minister who drew comparisons to John F. Kennedy after rising to power in 1968 on a wave of support dubbed "Trudeaumania". The architect of Canada's version of the Bill of Rights, Pierre Trudeau remains to this day one of the few Canadian politicians widely known to Americans.

Harper fought hard to reverse the policies of the Liberal Party in Canada, cutting corporate and sales taxes and removing Canada from a climate change agreement. The younger Trudeau wants to put Canada back on the course his father set, pledging to hike taxes on the rich and run deficits for three years to boost government spending and shore up a shaky economy.

Despite his grandiose beginnings, Justin Trudeau projects a more casual persona than his glamorous father, who dated movie stars such as Barbra Streisand, married, had children and divorced while serving as prime minister between 1968 and 1984, with a brief interruption.

A 43-year-old former high school teacher, Trudeau first captured national attention in 2000 with a moving eulogy at his father's state funeral. He challenged the country to cement Pierre Trudeau's vision of a united and multicultural Canada, moving many people to tears.

"It's all up to us, all of us now," he said then.

But it would be eight years later before Trudeau ran for office, winning a seat in Parliament representing a working class district of Montreal. By then, Harper had been in power for two years, intent on putting a distinctly more conservative face on the nation of 35 million people.

The Liberals, beset by years of infighting and ineffective leaders, had their worst electoral defeat in 2011 when they came in third behind the traditionally weaker left-of-centre New Democratic Party. But Trudeau increased his share of the vote in his own district and quickly rose to become the hope of his party, earning the leadership in 2013.

Harper's Conservatives pilloried Trudeau during the campaign as inexperienced. But Trudeau tapped into an appetite for change and worked his boyish image to project an approachability that belied his privileged background.

"He has an aura. He's very personable," said Stephen Clarkson, a political economy professor at the University of Toronto.

"People like Justin. He projects sincerity and interest and openness."

In his memoir , Trudeau discussed his turbulent upbringing. His mother, Margaret, was 22 years old when she married the 51-year-old prime minister in 1971, and she quickly earned a reputation for partying with the Rolling Stones and at New York's Studio 54. The couple had three sons but separated when Justin was six.

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Justin Trudeau and his brothers were raised by his father. His mother battled depression, particularly after the death of her son Michel, Justin's brother, in an avalanche in 1998.

"The truth is, my mother was very ill," Trudeau wrote. "She suffered a severe mental illness."

However, he wrote that he grew up free of much of the emotional trauma that divorce can inflict on children.

Trudeau, the second-youngest prime minister in Canada's history, now brings his own young family to Sussex Drive, the official residence in Ottawa. Married to former Quebec television host Sophie Gregoire, Trudeau has three children: Xavier, eight, Ella-Grace, six, and one-year-old Hadrien.