Justin Trudeau took only a few minutes after touring the University of Waterloo to take off his jacket and bound in front of a standing-room crowd at the Student Life Centre. For the next hour, he would speak without notes or Teleprompter, repeating questions into the mic so all could hear.

"What do I plan to do to engage youth in politics?" he said, looking around in mock surprise at the question, and then shrugged: "This."

His audience laughs. He points out that the student union has asked all party leaders to do the same. "Somehow, I don't think the Prime Minister is going to take them up on this invitation."

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It's self-serving, but rings true. It is hard to imagine Stephen Harper sauntering across a college stage in shirtsleeves, promising shorter answers so more people can ask questions, or generally doing things the way Justin Trudeau does. Sometimes that seems to be the point of Justin Trudeau.

He is the anti-Harper. If the Liberals did not have him, they would be trying to build him. In some ways, they are.

Whereas Mr. Harper often paints politics as choosing between right and wrong and "standing up" for principles, Mr. Trudeau has titled the autobiography he will publish this week Common Ground. One year from an election scheduled for Oct. 19, 2015, that book is part of a bigger brand-building.

As federal politicians swing into what is effectively the county's longest-ever election campaign, Mr. Trudeau has already given glimpses of his approach.

Between talks to students in Waterloo and the Chamber of Commerce in London, Ont., The Globe and Mail sat down with Mr. Trudeau, and found a man insisting that the process of building his political platform and approach is a key factor in setting him apart, and treating the policy platform as a final exam – insisting voters will be able to test his policy substance in the end.

"If, by the time they reach the ballot box, they're not satisfied that I have demonstrated that – yeah, they have a right to ask about that," he said. "In the meantime, a year out from the election, I'm not going to short-circuit some valuable conversations."

But it is all building around a contrast of personae, of approach, rather than policy details. Clearly, many Liberals around Mr. Trudeau think that if there is a sentiment for change next year, it will not be driven just by disagreement with Mr. Harper's policies so much as irritation with the way he does things after nine years in power. It is visceral. It will be a referendum on Stephen Harper's persona, and Mr. Trudeau wants to be the other side.

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And he is different. Mr. Trudeau keeps underlining it. Sometimes, he overreaches.

When opposing a Canadian combat mission in Iraq this month, he tried to show his reflexes are less war-like than Mr. Harper's – but slipped into a glib blooper, warning Canada should not "whip out our CF-18s to show how big they are." It played into his weakness: the perception that while Mr. Harper takes things seriously, Mr. Trudeau is not serious.

When it came to time to repair the damage, former prime minister Jean Chrétien stepped forward to defend his position on Iraq – a telling sign that the Liberal leader needed to borrow a cup of gravitas from a heavyweight.

He is open to charges he lacks policies. That has become a half-truth: He has taken stands on not reviving the gun registry, oil pipelines, RESPs, corporate taxes, the Senate, abortion, and yes, legalizing pot. But it is still a hodge-podge with many gaps. Parties have typically waited for the writs before releasing platforms, but his opponents, notably the NDP, are revealing policies early – pressuring him.

But as he speaks to students or supporters or business people on key electoral turf along southern Ontario's Highway 401, many of the issues he raises underline the contrasts with Mr. Harper.

He talks about Mr. Harper's failure to hold a premiers' meeting, and suggests the country suffers without that kind of co-operation. He insists Mr. Harper is ideological: that his unwillingness to show concern for the environment is damaging Canada's economic prospects, encouraging other countries, and First Nations, to reject Canadian resources.

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He is specific about some things. He explains why he would keep corporate taxes unchanged, or why he favours the Keystone XL oil pipeline to the U.S. gulf coast but not the Northern Gateway through B.C.

There are also a lot of generalities. But amid vague statements about values are outlines of direction for his political strategy and his policy.

The next election, he told students in London, will be about the economy and how it treats those who feel vulnerable in the middle class. Mr. Harper will offer tax cuts, but Mr. Trudeau says he will offer policies he frames as pro-growth, like spending on infrastructure and job training.

Yes, he tells a questioner, a national daycare program should be a priority, but growth-oriented spending comes first, and he wants to see what the budget surplus will be.

On other social programs, you can learn Mr. Trudeau's approach, if not his policy. When a student asked about the high cost of tuition, the Liberal Leader said society has an interest in more people going to university, and so it should invest in that – up to the point where it is good for society as a whole. So instead of giving $1,000 to everyone who goes to university, it is better to give $5,000 to those people "for whom it makes the difference of going to school" or not. In other words, government should spend up to the point that it benefits society, not just the individual.

But of course, politics can get in the way of planning, and the real trick in policy is the details. Mr. Trudeau did not offer any.

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He insists he wants people to see an "iterative" process that they can join to develop policies where he outlines "how I see the issues, how I see finding solutions to the issues."

"I think it's a big contrast against what people see a lot in politics, which is, 'These are the talking points, this is what we're sticking to, and I'm broadcasting one way to you,'" he said in the interview in London. "I'm a teacher. I believe in sort of sharing in a discussion and coming out of it with new insights on both sides."

It may not be so easy to stick with such a long process. The NDP is releasing policies now – it has already proposed a national child care plan. If Mr. Trudeau does not reply for seven months, he may find himself again facing the perception that he lacks substance.

While Conservatives complain Mr. Trudeau tops opinion polls without a complete policy book, there is another side of the equation: Mr. Harper has slipped and his policies are not really the problem.

Polls regularly show a plurality of Canadians approve of Mr. Harper's handling of the economy or foreign policy. Ipsos-Reid found 49 per cent of Canadians approve of his record – but 67 per cent want another party to take over.

Perhaps it is Mr. Harper's persona that polarizes. When another pollster, Angus Reid Global, asked Canadians what attributes they ascribe to world leaders like Mr. Harper, the composite was that he is secretive but strategic.

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Those who voted Conservative in 2011 think he is strong and credible. Those who voted NDP or Liberal called him uncaring and a bully.

Many Liberals say they think that, outside his Conservative support base, irritation with Mr. Harper is solidifying. Perhaps people who feel that way will be motivated to turn out to vote, and to band behind whoever is more likely to beat him. Perhaps they will look to someone who strikes them as very unlike Mr. Harper.

And if they want a contrast of style, it is more likely to be Mr. Trudeau than Thomas Mulcair. The NDP Leader is sharp and strong-willed, but seen as scarcely more upbeat than the Prime Minister.

The other side of embracing Mr. Trudeau's contrasts with Mr. Harper is emphasizing what people like about the PM.

"The number one thing the Prime Minister has going for him is that he's serious," one former aide said. Even people who do not like him think he works at it, and is credible. He likes to make tough decisions, and people see that. He is not trying to look warm and fuzzy. "He doesn't want people to see him as the guy you'd have a beer with. He says the job is making decisions."

The plan is to use a team – star candidates, a former general, and economic players such as Morneau Sheppell chair Bill Morneau or former Business Council of Manitoba president Jim Carr – to counter the public's questions about whether Mr. Trudeau has the same substance.

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Liberals say their leader is not too proud to hire and rely on the right people. Now the question is whether Canadians will want a political chairman of the board, or a hands-on CEO like Mr. Harper.

There is no doubt Mr. Trudeau has remodelled Canadian politics, taking his third party in the Commons to front-runner in the polls.

Does he think Canadians take him seriously now? His eyes darken when he answers: "My opponents do."

It is clear that many voters have not drawn their conclusions yet. In every crowd, there is interest, and those who ask for pictures, and leave smiling. At the University of Western Ontario, he followed an hour-long, no-notes talk to students with 20 minutes of posing for selfies with them. But some are disappointed. They want to know where the contrasts lead.

"The only thing I'd heard about Trudeau was the weed thing, and I was hoping he'd have some other ideas," said Alex Tonelotto, a 20-year-old international relations student. "It was more general. Bring Canada together – what does that mean?"

If you met the federal party leaders on the campaign trail, what would you ask them? Post your question to Facebook, or Tweet or Vine it with #VoteCountdown. Take a look at what readers have already suggested.