Justin Trudeau has promised to end a decade of divisive politics, vowing to unite Canadians and embrace diversity.

"I will be the prime minister of all Canadians," he told a crowded rally in Montreal after winning a historic Liberal majority government.​

Trudeau credited his stunning electoral success to an "old-fashioned strategy" — meeting and listening to Canadians. He committed to lead a government that is hard-working, transparent and inclusive, reaching out to Quebecers, aboriginal people and ethnic minorities.

"We beat fear with hope. We beat cynicism with hard work. We beat negative, divisive politics with a positive vision that brings Canadians together," he said.

The Liberal win is a remarkable finish for a party that began the race in third place 11 weeks ago. A swell of support that grew in the second half of the campaign was reflected as soon as early voting results began to trickle in from Atlantic Canada.

The party took all 32 seats in Atlantic Canada, a Liberal wave that rolled right across the country.

Appointing a cabinet

One of prime minister-designate Trudeau's first orders of business will be to assemble a cabinet, and he will likely bring a mix of former ministers and fresh blood to his front bench.

Experienced veterans like Ralph Goodale, Scott Brison, John McCallum and Stéphane Dion could be at the table with newcomers such as former Toronto police chief Bill Blair, former Crown prosecutor and regional chief of the Assembly of First Nations Jody Wilson-Raybould, and Toronto businessman Bill Morneau. Two former high-ranking Canadian Armed Forces officers, Andrew Leslie and Karen McCrimmon, could also be in line for posts.

Gerald Butts, principal adviser for the campaign, said Trudeau will talk to a "key group" of people about a transition plan.

He said the campaign was a success because Trudeau spent the last three years talking to Canadians.

"It's true we got lots of advice from experts on our economic plan, but at the end of the day he was the person who was able to decide whether it was going to ring true with what Canadians wanted, because he'd had thousands and thousands of conversations with regular people," Butts told CBC News.

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Over the course of the campaign's 78 days, Trudeau cast himself as the best choice over NDP Leader Tom Mulcair to bring in change and oust Stephen Harper's Conservatives.

Communications consultant and political observer Barry McLoughlin said the millions of dollars in advertising spent by the Conservatives to discredit Trudeau as "Just Not Ready" actually had a positive effect on the Liberal campaign.

"They were successful in driving down the expectations," he said.

Trudeau's performance in the first debate hosted by Maclean's magazine did appear to put him back in the race. The party climbed three points in the following week, and that support began to build after a string of debates that ended Oct. 2. The Liberals managed to break a tie with the Conservatives and build momentum to the finish.

McLoughlin said Trudeau also benefited from confronting the "elephant in the room" — his relative lack of experience — by handling criticism in a mature manner and transforming it into a message of compassion and energy. He remained largely sunny and upbeat, delivering clippable and quotable lines and staging memorable photo ops.

Liberal Leader Justin Trudeau waves to supporters. (Paul Chiasson/Canadian Press)

"They created an energized, youthful-oriented campaign," McLoughlin said.

Gerald Baier, political science professor at the University of British Columbia, agrees the marathon worked in Trudeau's favour.

The Conservatives thought an extended campaign would give Trudeau more time to make mistakes, but it actually gave him more time to beat back criticism and present himself as the "fresher face" of the three main leaders.

"He had 78 days, and the more he was out, the more he was able to connect with voters," he said. "It helped him more than hurt him."

Baier said leaders' debates and the decision to run three consecutive deficits were "turning points." With the economy a crucial issue Trudeau was taking a big gamble, but Baier said it worked to differentiate himself from Mulcair, who promised to balance the books.

Tale of 2 Trudeaus

The 43-year-old Trudeau is the first son of a prime minister to become a prime minister. He will follow in his father's footsteps, moving his young family into 24 Sussex Dr.

The Trudeau political legacy has been both historic and polarizing, with Pierre Elliott Trudeau bringing in policies of bilingualism, multiculturalism and the Charter of Rights and Freedoms that some consider core Canadian values. But there is also the lingering resentment over controversial policies in Western Canada and Quebec, including the National Energy Program and invoking the War Measures Act.

Trudeau shakes hands with Conservative Leader Stephen Harper, as Green Party Leader Elizabeth May greets NDP Leader Tom Mulcair, right, following the Maclean's leaders' debate in Toronto on Aug. 6. (Frank Gunn/Canadian Press)

Charm and charisma are also part of the Trudeau family legacy.

Alex Marland, a political scientist at Memorial University in St. John's, said this campaign was driven by personality politics and the "celebritization" of leaders over more substantive issues.

"Despite the campaign's extraordinary length, we heard relatively little about the finer details of political parties' platforms, or about their potential cabinet members or candidates," he said.

He called it "telling" that Trudeau was not targeted by an onslaught of personal attack ads to counter his surge in the final days of the campaign.

"I suspect that this is because of many Canadians' para-social attachment to Justin Trudeau, who has grown up in the public eye, and who is charismatic. How else to explain why the Conservatives or NDP did not release a last-minute advertising campaign that provokes fear on the scale that we have seen in the past?"

The Liberal comeback is a rebound from the worst defeat in the party's history, in the May 2, 2011, federal election. The party finished in third place, with only 19 per cent of the vote and 34 seats.

Trudeau, a former high school teacher, was first elected in 2008 in the riding of Papineau. The father of three becomes the second-youngest Canadian prime minister in history, after Joe Clark, who was 40.

He is married to Sophie Grégoire-Trudeau.