Canadian Prime Minister Justin Trudeau got his wish last Sunday. The governor general dissolved Parliament two years ahead of schedule and voters will be going to the ballot box Sept. 20. Four major national parties — the Conservatives, the Liberals, the socialist New Democrats and the Greens — will be contesting the election, as well as the Quebec separatists of the Bloc Quebecois.

Trudeau, riding high in the polls after almost doubling federal spending to address the coronavirus pandemic, is betting that voters will reward his Liberal Party with a majority of the seats in Parliament. For the moment, the other parties are simply trying to hang on to their current seats.

With Canada now in its fourth wave of coronavirus infections, Trudeau says that the election is about determining a Liberal Party mandate to rebuild the country after the pandemic. Opposition parties counter that the Liberals have always received enough support to get their bills through Parliament and there is no clear policy issue voters are being asked to decide. If voters believe that there isn’t a reason to hold an election during the fourth wave of the pandemic beyond Trudeau’s personal ambitions, they could quickly turn on him.

What’s behind Trudeau’s gamble?

Canada’s last national election was less than two years ago, with the Liberals winning just shy of a majority in the House of Commons. As a result, they need the support of just one of the other three main opposition parties to govern, and they’ve negotiated this with opposition parties on a bill-by-bill basis.

Trudeau and the Liberals are betting on a better outcome this time. The Liberals’ covid-19 support package, which included direct payments to almost 9 million Canadians temporarily out of work during the pandemic, cost over 10 percent of the gross domestic product. Canadians responded to this assistance by giving the Liberals a five-point lead in the polls.

According to analyst Éric Grenier, the Liberal party has an 88 percent chance of winning the most seats and a 37 percent chance of winning an outright majority, which would allow the Liberals to govern unopposed for four years.

Who’s Erin O’Toole?

The Conservatives are Canada’s largest opposition party — and the only one that has ever formed government. Erin O’Toole became the party’s chief a year ago, after the Conservatives ousted their previous leader for failing to win the 2019 election. O’Toole ran as a true-blue Tory, banking on appeals to his party’s socially conservative wing. He quickly shifted gears once he won the leadership in an attempt to win moderate suburban voters, particularly around Toronto. Since then, he has failed to gain traction against Trudeau. During the pandemic, frequent announcements by the prime minister and public health officials dominated the national news. And travel restrictions prevented O’Toole from crisscrossing the country and introducing himself to voters. Polling data suggest almost half of Canadians don’t know his name — and currently give the Conservative Party just 29 percent of the vote, near historic lows.

How will the opposition parties split the vote?

It isn’t just the Conservatives who are floundering. The other national opposition parties — the socialist New Democrats and the Green Party — are having trouble, too. The Greens, in fact, spent the summer debating whether to expel their leader, Annamie Paul, from the party.

Paul’s senior adviser had called two of the party’s three MPs antisemitic for their comments about the Israeli-Palestinian conflict and she stood by the adviser, creating an internal schism. The party had to lay off staff to cover legal expenses after its board considered expelling Paul due to the schism, and the affair has hurt Paul’s chances of winning her own seat in Parliament.

But weak left-wing support also hurts the Tories. Canada is divided into 338 electoral districts, called ridings, and the candidate that wins the most votes in a riding wins its seat in the House of Commons. The party that can command the support of the majority of the House forms a government, with its leader becoming prime minister.

With four national parties, having another party siphon off votes from your closest rival is also critical. This means Trudeau is in an excellent position at the moment. The Greens’ infighting and the New Democrats’ low poll numbers means he can devote all his energies to defeating O’Toole.

Is there a coronavirus wild card?

While Trudeau and the Liberal Party seem to be in command, the ongoing pandemic has introduced some uncertainty. Canada currently has one of the world’s highest vaccination rates, and the summer has seen a progressive easing of lockdowns. That ended Tuesday when the Ontario government suspended its reopening plan due to concerns about the delta variant.

In the spring, when Trudeau began to consider holding a fall election, he had hoped that the coronavirus would be under control. Now his own chief public health officer is saying that the delta variant could overwhelm the medical system by the fall.

The opposition parties are keen to capitalize on the idea that the prime minister is more interested in his own electoral fortunes than the health of Canadians by calling an election now, less than two years into a four-year mandate. Meanwhile, the government agency that runs the election has geared up for an increase in mail-in voting.

Tyler Kustra has been a visiting fellow at Harvard University and has served as an economic adviser to the Parliament of Canada. He is currently an assistant professor at the University of Nottingham.