The New Democratic Party NDP having leading in 27 emirate districts, will be key in enabling the Liberals to pass laws in the 338 seat House of Commons after Trudeau's party fell shy of the 170 seats needed for a majority.
The left-leaning party has pushed for higher taxes on the rich, government-funded drug and dental care, raising the minimum wage and cancelling student debt. The NDP is expected to demand concessions on its priority issues in exchange for support.
Without it, the Liberals could lose key parliamentary votes and cause another election.
Trudeau promised to require vaccinations for federal government employees, workers of domestic industries like airlines and Federally regulated travelers on planes and trains.
Quebecers are going to expect him to enact the mandates soon, with a fourth CoVID - 19 pandemic wave surge in most populous provinces and Western province of Ontario. Canada has one of the world's highest vaccination rates, but it has stalled over 68% of the population.
Forest fires in Western Canada and a drought in the crop producing areas are focusing on climate change.
The Liberals have promised to cut national emissions by at least 40% from 2005 levels by 2030 and add a new requirement in 2025 for the oil and gas sector to reduce emissions by an undetermined rate
They have given little detail about how they will achieve their goals, but are expected to flesh out a strategy to back construction of massive hubs to capture carbon.
To tackle the pandemic, the Liberals run up a record national debt of C $1 trillion $785 billion and pushed budget deficits to highs not seen since World War Two.
Their campaign will deliver a further C $78 billion in new spending over five years, including pledges for a national childcare program and an increase in affordable housing supply by building, conserving or repairing 1.4 million homes over the next four years.
The Liberals said they would raise the net tax rate on banks and insurance companies.
Trudeau called the election to hope that Canada's successful COVID - 19 vaccination plan would enable the Liberals to win a majority.
Their failure raises questions about his own future, and he may face pressure to quit, allowing a new leader to put a new face on the party before another election.
Finance Minister Mark Carney and former Bank of Canada Governor Chrystia Freeland figure in speculation as possible replacements.
Early on Tuesday, Trudeau told supporters that the results meant he has a clear mandate.