Campaigning for Canada’s federal election on 21 October formally began on Wednesday, as Justin Trudeau seeks a second parliamentary majority from an increasingly divided electorate.

The prime minister met the governor general, Julie Payette, to officially request the dissolution of parliament, and formally start the election campaign, which will see party leaders crisscrossing the vast country to pitch to voters.

“We’ve done a lot together these past four years, but the truth is, we’re just getting started. So Canadians have an important choice to make. Will we go back to the failed policies of the past, or will we continue to move forward?” Trudeau told reporters gathered outside Payette’s residence, Rideau Hall.

The prime minister also used his speech to make sharp distinctions between his administration and a potential government led by the Conservative party.

“It’s going to be different from elections we’ve seen over the last couple of decades. There’s deep polarisation in the country,” said Frank Graves, president of the polling company EKOS Research. “On issues such as climate change, immigration and attitudes towards public institutions, the divisions have never been starker.”

The upcoming campaign will last nearly six weeks: half the length of the marathon campaign of 2015, when voters endured almost 80 days of mudslinging by political leaders – a brief dash compared to US elections, but a marathon for Canada.

Trudeau, who swept to office in November 2015 promising “sunny ways” and stressing the importance of gender equality and the environment, faces an electorate which will be much more focused on the economy.

The country’s 43rd election also comes against the backdrop of protracted political scandal for the incumbent prime minister.

For months, Trudeau has faced accusations – including from the country’s ethics commissioner – that he acted improperly when he requested his attorney general to halt criminal prosecution of the Quebec-based engineering giant SNC Lavalin.

Trudeau and his Liberals are widely expected to use the election to shore up support for his government’s climate change policies, including a nationwide carbon tax. His main opponent, the Conservative leader, Andrew Scheer, has pledged to repeal the Liberals’ marquee environmental legislation.

Scheer, the youngest federal leader and running in his first federal campaign as head of the party, has consistently used the prime minister’s ethical lapses to paint the government as unable to govern effectively.

Polling suggests Trudeau and Scheer are deadlocked in the popular vote, but the Liberals hold an edge when it comes to winning seats in parliament.

Jagmeet Singh, leader of the leftwing New Democratic party, is also running his first federal campaign as a party leader. Despite initial excitement around his role as the first major party leader from a racial minority, the NDP’s finances have collapsed and the party is likely to sustain heavy electoral losses throughout the country. “They are in danger, if they were to slip any more – which I would not rule out – of not forming official party status,” said Graves.

Meanwhile, the Green party, led by Elizabeth May, has experienced a surge in support as the climate crisis increasingly rates as an important issues for voters.

The official start of the campaign comes a day before a highly anticipated leaders’ debate, in which Scheer, Singh and May will spar for the first time on stage. But the televised debate, hosted in Toronto, will have a glaring omission: Trudeau has opted to skip the event, leaving his rivals without a foil.