MONTREAL -- Liberal Leader Justin Trudeau on Sunday pitched his party as the only one that can stop Erin O'Toole's Conservatives from forming government as he crossed the country in a flat-out sprint for last-minute votes.

The day before Monday's federal election, Trudeau began by telling some 300 supporters at an outdoor rally in Montreal that progressive voters don't have to choose between blocking the Conservatives and picking the party with the "best, most ambitious progressive plan" on climate change, child care and supporting families.

"Because the answer to both those questions is the Liberal Party of Canada," Trudeau told the cheering crowd.

The Liberal leader's whirlwind final day of campaigning saw him begin in Quebec before travelling to Ontario and Manitoba, while holding virtual events in other regions. His day was expected to end near midnight at a rally in the Vancouver area before flying back to Montreal in the early hours of the morning for election day.

As he has throughout the campaign, Trudeau on Sunday sought to portray O'Toole as a leader who will "take Canada backwards" by rolling back greenhouse gas reduction targets and cancelling $10-a-day child care deals with the provinces.

As he gestured on stage to a sea of cheering red-and-white clad Liberal supporters gathered on a brewery patio, he hammered the Conservative leader for refusing to mandate COVID-19 vaccinations for his candidates, and accused him of protecting the anti-vaxxers in his party by telling even his vaccinated candidates not to disclose whether they've received the shots.

But with polls showing the Liberals and Tories locked in a dead heat, Trudeau also tried to draw Green and NDP voters in recent days, saying those parties' environmental platforms are less ambitious and achievable than his own.

Trudeau has spent most of the last week of his campaign focusing on the key battlegrounds of Ontario, British Columbia and Quebec, where his party needs to hold or increase support.

On Sunday morning he also turned his attention to Alberta, where the conservative government of Premier Jason Kenney recently reimposed public health restrictions following a surge in COVID-19 cases and warnings the health care system is on the brink of collapse. Trudeau told reporters following the rally that an O'Toole government would lead the country down a similar path.

Trudeau has also been dogged by criticism from his rivals and some members of the public for dissolving the minority parliament and calling an election during the fourth wave of the health crisis.

Trudeau in the final days of the campaign has largely traded suits for jeans or khakis and running shoes, has ditched his TelePrompTer and campaigned at a blistering pace, sometimes visiting five or six ridings a day.

He's been swarmed by adoring fans who clamour for selfies during walkabouts in farmers markets and on scenic main streets, and heckled by small groups of angry protesters who accuse him of ruining the country and hurl insults his way.

After the Montreal rally Sunday morning, he flew to Ontario for a backyard barbecue in King-Vaughan, north of Toronto, alongside incumbent MP and cabinet minister Deb Schulte.

Among the crowd was neighbour Rashid Manliaza, a 30-year-old father of two young children, who said he's not a Liberal volunteer but supports the party's promise of affordable daycare.

"So if it (becomes) $10 a day I can afford that, and my wife can look for a job," he said, adding that daycare costs in the region are between $50 and $100 a day.

Another attendee, Suraj Dhoum, said she has proudly cast a Liberal ballot since the days of former prime minister Pierre Elliott Trudeau -- the current leader's father -- because she felt his policies welcomed her when she immigrated from India in 1974.

Earlier Sunday, Trudeau once again refused to outright ask voters to give him a majority, telling reporters after the Montreal rally that his goal is to send as many Liberal MPs to Ottawa as possible.

But Melanie Joly, one of Trudeau's outgoing cabinet ministers, said she wants the party to have a "strong mandate" with "both hands on the wheel."

In Quebec, the party has had to face a challenge from a Bloc Quebecois party that has tried to make political hay from an English-language debate question that described the province's secularism bill as discriminatory.

While Trudeau and other leaders denounced the question after the fact, the incident has given a boost to Bloc Leader Yves-Francois Blanchet, who has argued he's the only leader to truly defend Quebec's interests.

This report by The Canadian Press was first published Sept. 19, 2021.