The numbers suggest the Montreal MP is well on his way to a decisive first ballot victory on April 14.
At the same time, a new poll suggests stepped-up attacks on Trudeau by some of his rival leadership contenders have done nothing to dim his appeal among Canadians in general.
Some 39 per cent of respondents to The Canadian Press Harris-Decima survey said they'd be certain or likely to vote Liberal if Trudeau was at the helm.
That percentage has remained unchanged since the start of the leadership contest last November, suggesting Trudeau is not the flash-in-the-pan celebrity some of his rivals have tried to make him out to be.
The poll suggests Trudeau could siphon off support from all other parties: 39 per cent of New Democrats, 33 per cent of Greens, 22 per cent of Conservatives and 12 per cent of Bloc Quebecois supporters identified in the poll said they'd be certain or likely to vote Liberal if Trudeau was leader.
Under rival Marc Garneau — a former astronaut who has repeatedly cast Trudeau as an untested, inexperienced lightweight offering little but platitudes — 26 per cent said they'd be certain or likely to vote Liberal.
Under former MP Martha Hall Findlay, who apologized after questioning how Trudeau could understand the challenges facing middle-class Canadians given his privileged upbringing, the number shrank to just 15 per cent.
The number of certain or likely Liberal voters shrank even further, to 12 per cent, under the leadership of lower-profile challengers Joyce Murray, Martin Cauchon, Deborah Coyne and Karen McCrimmon and to just nine per cent under David Bertschi.
The telephone poll of 1,000 Canadians was conducted Feb. 21-24 and is considered accurate within plus or minus 3.1 percentage points, 19 times in 20.
While repeated polls have suggested the party would fare best under Trudeau, a factor that will undoubtedly influence Liberals as they choose their next leader, they are not necessarily predictors of how the leadership contest will shake out.
Only those who signed up as Liberal members or supporters as of last Sunday are eligible to vote.
Party president Mike Crawley disclosed Wednesday that there are now 294,002 eligible voters. Most are believed to have taken advantage of the party's new supporter class to sign up for free, although the party has provided no breakdown.
Trudeau's team initially claimed it had signed up 150,000 people but insiders now say the number is between 160,000 and 165,000.
However, only eligible members and supporters who register to vote over the next two weeks will actually be entitled to cast ballots during the week of April 6-14.
The party is using the registration process to weed out those who may have been signed up without their knowledge and to verify identities and addresses of supporters. The addresses matter because the results of the leadership vote will be weighted to give equal clout to each riding.
Others who signed up on a whim may not be sufficiently interested to fill out the registration form, which requires them to affirm support for the Liberal party and its purposes, that they are Canadian citizens, at least 14 years of age and not a member of another federal party.
Inevitably, the number of registered voters will be less — perhaps substantially less — than the almost 300,000 eligible voters the party is now boasting. And even fewer will likely go all the way to casting ballots.
During last year's NDP leadership contest — which allowed only dues-paying members to vote and did not require a special registration procedure — less than half the roughly 130,000 eligible voters actually cast ballots.
Trudeau said late Wednesday he's taking nothing for granted, that the task now is to convert all those who signed up into registered voters.
"It still remains to be seen how many of those people will come out and vote and how many of those people will come out for us. And therefore, we're keeping the extraordinary work that a very committed team right across the country is going to keep up."
Murray, who received a late burst of momentum from a host of online and grassroots advocacy groups, said she expects a high voter turnout among her supporters because they're committed to her plan for electoral co-operation and sustainability.
"I'm very happy with where we're at and I think we have an opportunity to surprise people on April 14," the Vancouver MP said in an interview.
Interim Liberal leader Bob Rae said his party intends to "pull out all the stops" to persuade as many eligible voters as possible to register and vote.
But even if a big chunk of eligible voters do not take the next steps, Rae said the experiment with the new supporter class will still be a huge success. It has already provided the party with the names and contact information for thousands of new "sympathizers" who can be tapped for donations, support during elections and policy development.
"The fact that we've now got 300,000 people who are in a universe that we can identify and continue to be in touch with those people is very positive in and of itself," Rae said.
Also on HuffPost