OTTAWA -- Canada's political landscape is poised for a potentially seismic shift today as federal Liberals anoint a new leader they hope will re-establish their reputation as the country's natural governing party.

The outcome is pretty much a foregone conclusion: Justin Trudeau, eldest son of former prime minister Pierre Trudeau and the party's undisputed rock star, is widely expected to win handily.

His ascension to the Liberal helm will, at least in the short term, put paid to the notion that the next election will be a polarized two-way fight between the Conservatives and New Democrats, with the Grits destined for oblivion.

Just the prospect of the 41-year-old Montreal MP's victory has already boosted the Liberals, reduced to a third-place rump in 2011, back into contention in public opinion polls. They are now running even with or ahead of the ruling Conservatives. The NDP has been relegated to its traditional third place slot after vaulting into official Opposition status in 2011 for the first time in its history.

Whether Trudeau can maintain that momentum until the next election in 2015 remains to be seen. But he has so far defied his detractors who were certain six months ago, when he launched his leadership bid, that his popularity would prove to be fleeting.

With a Trudeau win in today's leadership announcement virtually guaranteed, the only real question that remains is the magnitude of his victory.

Most party insiders -- including realists in the five rival leadership camps -- are privately predicting a comfortable first ballot win, with Trudeau taking anywhere from 60 to 80 per cent of the votes cast.

Vancouver MP Joyce Murray is widely thought to be a distant second, boosted by grassroots and online advocacy groups that have endorsed her strong environmental stance and her plan for one-time electoral co-operation among progressive parties to ensure defeat of Stephen Harper's Conservatives in the 2015 election.

She has secured some high-profile endorsements from the likes of former cabinet minister Lloyd Axworthy and environmental guru David Suzuki. And she's pulled in the second largest pot of cash -- almost $250,000 from more than 2,200 contributors, according to the final financial reports filed with Elections Canada.

Money magnet Trudeau's final report is yet to be posted but he has previously reported raking in almost $1.1 million from some 8,500 donors.

While the campaign has boosted Murray's previously low profile and positioned her as a champion of the party's left wing, she would likely have to finish a relatively strong second -- upwards of 20 per cent -- to claim any real influence over Trudeau's agenda. That appears doubtful.

Former Toronto MP Martha Hall Findlay, who cast herself as a champion of business-friendly Liberals, is thought to be running close behind Murray, followed by former cabinet minister Martin Cauchon, with Toronto lawyer Deborah Coyne and retired military officer Karen McCrimmon bringing up the rear.

The process the party has adopted for choosing its next leader makes it difficult to pin down the outcome with any precision.

The geographic distribution of each candidate's support could skew the results somewhat, not likely enough to make much difference to Trudeau but potentially influencing the order in which the dark horse contenders cross the finish line.

The results will be weighted to give each of the country's 308 ridings equal clout. Each riding is allotted 100 points, to be assigned proportional to each candidate's share of the vote in that riding.

Hence, a candidate who wins 50 per cent the votes in a riding will win 50 points, no matter if 100 votes are cast or 1,000.

A total of 30,800 points are up for grabs. The winning candidate will have to score at least 15,401 points.

Trudeau's team maintains his support is fairly evenly distributed across the country. The dark horse contenders have attempted to boost their positions by concentrating their support in ridings with the fewest voters.

The contest has been an experiment for Liberals, who decided to allow a new class of supporters -- not just dues-paying, card-carrying members -- to vote for the next leader.

Almost 300,000 supporters signed up to participate in the contest. But just over 40 per cent of them actually registered to vote.

Still, the party has gained valuable contact information from the supporter sign-ups, which it hopes will help build the kind of modern data base required for political fundraising and voter identification in election campaigns.

Among the 127,000 who did register to vote, turnout is high -- as of Saturday evening, more than 96,000 or 76 per cent had cast ballots online or by phone. That's well above the 65,000 New Democrats who voted in last year's NDP leadership contest, which elected Tom Mulcair. And it's close to the record 97,000 who voted in the 2004 Conservative contest that chose Stephen Harper.

Liberals have until 3 p.m. (ET) Sunday to cast ballots.