The Liberals have continued to make important gains in national support with Justin Trudeau at the helm, as polls taken since his leadership victory give the party a roughly seven-point advantage over the governing Conservatives. But building a successful electoral coalition may be more difficult than it appears.

A weighted average of the latest national polls gives the Liberals 36 per cent support, a gain of six points since the last aggregation calculated before Mr. Trudeau officially became party leader. The Conservatives have dropped a single point to 29 per cent, while the New Democrats have slipped three points to 23 per cent. The Greens and Bloc Québécois have 6 and 5 per cent support, respectively.

The surge in Liberal support since Mr. Trudeau's leadership victory has been consistent across the surveys that have been conducted in the last few weeks. Though other leaders, most recently Stéphane Dion and Michael Ignatieff, have experienced similar bumps after becoming leader, Mr. Trudeau's honeymoon is of a different magnitude. The party was polling at only 23 per cent as recently as January, and the last leader to have so dramatically increased a party's support from its previous election showing was Brian Mulroney.

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The Liberals, Conservatives, and New Democrats have placed first-second-third in the last six polls, including two that were conducted even before Mr. Trudeau became leader, and in eight of the last nine. The Liberals have registered 35 per cent or more support in all four polls that have conducted since his leadership win, while the Conservatives have been under 30 per cent in three of the last five and the NDP has been at 25 per cent or lower in the last six. These are rather significant trends.

But Mr. Trudeau's support may not be as efficiently spread across the country as it could be. Despite holding a seven-point lead, it is estimated that with the regional support the polls are showing the Liberals would tie the Conservatives in seats with 115 apiece, if an election were held today. The NDP would take 69 seats, the Bloc Québécois eight, and the Greens would retain their one.

The seats that are scheduled to be added to the electoral map before 2015 do not change things much: on those boundaries the Liberals would likely capture 127 seats to 126 for the Tories and 76 for the NDP.

There are a few issues blocking an easy path to victory for the Liberals. The Conservatives have maintained a wide lead in Alberta and the Prairies, giving them dominion over the vast majority of seats in the three provinces. By contrast, the Liberals only have that sort of advantage in Atlantic Canada, where there are half as many seats.

In Ontario and Quebec, the Liberals are not working from a good base. Running up the vote in Toronto and Montreal will win them few seats outside of the two main cities. Mr. Trudeau will need to work to appeal to Ontarians outside of Toronto and to francophone Quebecers in order to win more seats. There are some indications, however, that under Mr. Trudeau the Liberals are under-going a renaissance among French-speaking Quebecers. It has yet to be confirmed.

But the New Democrats are far from being wiped from the map in the province. The Liberals now hold a 10-point lead in Quebec over the New Democrats with 37 to 27 per cent support (a gain of six points for the Liberals since the beginning of April), but the NDP is still capable of winning some 30 seats with those numbers in the province. Nevertheless, there are some worrying signs for the NDP: the Liberals have scored 37 per cent or higher in five consecutive, post-leadership polls in Quebec, including one from Quebec-based CROP.

In Ontario, the Liberals have a narrow three-point lead over the Conservatives with 38 to 35 per cent support. That represents a gain of four points for the Liberals in the last month, almost all of which has come from the New Democrats, who are down to 21 per cent. The Conservatives, however, seem to have hit a bit of a floor in the province and would still be capable of winning 40 to 50 seats, and as many as 60 with the new ridings even with these levels of support.

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Voting intentions in British Columbia are a little more complicated, with the three parties in a tight race: 30 per cent for the NDP and 29 per cent for both the Liberals (up six points) and Conservatives (down three). The Greens are still polling strongly here, at 10 per cent. But the effect of the provincial campaign may be skewing the numbers in B.C. If it is not having a large impact on the polls, however, then the fact the Liberals have been at 30 per cent or higher in five of the last seven surveys in the province represents a key breakthrough.

The important question is whether or not the Liberals will be able to sustain this momentum straight through to 2015. More likely than not, something will occur between now and then to muddy up the works for Mr. Trudeau's team and his novelty could very well wear off. But for the Liberals to have almost doubled their vote share since their disastrous electoral showing of 2011 in a matter of only two years is not something to be taken lightly. The last time such a dramatic shift in voting intentions occurred in the polls, it propelled Jack Layton's New Democrats to new heights in Quebec and from fourth place to a historic Official Opposition status in the House of Commons.

ThreeHundredEight.com's vote projection model aggregates all publicly released polls, weighing them by sample size, date, and the polling firm's accuracy record. The seat projection model makes individual projections for all ridings in the country, based on the provincial and regional shifts in support since the 2011 election. Projections are subject to the margins of error of the opinion polls included in the model, as well as the unpredictable nature of politics at the riding level.

Éric Grenier writes about politics and polls at ThreeHundredEight.com .