Before Christmas, I wrote about both the Conservatives and New Democrats, and have been mulling the situation of the Liberal Party a bit longer.

In 2013 the Liberal Party made a choice with huge implications.

After watching its performance at the polls spiral downward for years – losing seats, money, visibility and public interest – a change in trajectory was critical, not only to success, but to survival.

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And change the trajectory did, when Justin Trudeau was elected by a huge majority of party members and supporters. Skeptics wondered whether he would run a solid campaign for the leadership, and he proved them wrong. Doubters thought he might struggle with the challenges of leading a party in third place with a mess of problems.

After nine months, he's won key by-elections, attracted good candidates, is raising more money from more people than the Liberal Party ever has before and is ahead in the polls. Momentum is the term that comes to mind.

His opponents seem convinced he will fade in the stretch, wilt under the pressure, collapse in a leadership debate, etc. etc. For their sake, that had best not be their whole strategy. They might want to have a plan B.

But if the choice the Liberals made in 2013 carried huge consequences, the choices to be made in 2014 will be no less important.

Support for the Liberal Party has risen for three reasons: the appeal of Mr. Trudeau, frustration with the Conservatives and uncertainty about NDP economics. The safe assumption for the Grits is that both the other parties will not be standing pat, but instead making efforts to address their challenges.

The Liberals will need to choose between a relatively passive strategy and one that is more disruptive.

A passive strategy would focus on raising money, choosing good candidates and building a volunteer organization, but otherwise staying on the sidelines of political conflict between the Tories and the NDP, banking that the other parties will continue to struggle with their unique afflictions, and voters will drift towards the Liberals.

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An active strategy would mean adding definition to the still fairly loose shape of Justin Trudeau's proposition. The goal would be to turn hope about Mr. Trudeau into confidence that he is ready to lead Canada.

Often, in politics, the best results are achieved by those who are most determined to improve. Incumbents founder when they are unable to see, let alone improve on, their own flaws. Canadians appreciate humility and love underdogs. Mr. Trudeau seems to understand and embrace this to good effect.

He also sees opportunity in the idea that hyper-partisanship is not just an annoying reality we all have to live with as the price of competition in democracy. That times have changed.

Lots of first-time and swing voters are fed up with those who seem to be in politics to fight other partisans more than to do the right thing for the country. For them, Mr. Trudeau is easily the least partisan sounding of the main party leaders.

In 2014, his challenge is to hold on to those advantages while finding ways to illustrate and build confidence in his decision-making skills. The policies he promotes, the ideas he rejects, the arguments he engages on, the ads he puts on air, the interviews he does…all will carry greater importance. He's heading into an 18-month final exam.

The positions he's taken so far are hardly risk-free, and to succeed, he may need to revisit some of them. Looming choices over energy and pipelines are complex, especially for someone with his last name and his party's history. He'll also get pretty fed up with how much he'll need to talk about pot, and especially the weedier issues such as distribution.

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His pitch is to the 70 per cent of Canadians defined as "middle class," but who are really better understood as "middle of the road" pragmatists. Some of his own partisans will press him to move hard left; some will pull him in the other direction. In 2014, he'll settle more of these questions, and reveal more about what he's made of. If the choice of Mr. Trudeau made waves in 2013, his choices in 2014 will roil the waters even more.

Bruce Anderson is the chairman of polling firm Abacaus Data, a regular member of CBC The National's "At Issue" panel and a founding partner of i2 Ideas and Issues Advertising.