In the upcoming federal election campaign, Prime Minister Justin Trudeau will debate his fellow party leaders in English only once. In French, however, he'll do it twice.

That's because a lot of the voters who will be tuning in to that second French-language debate are among the most coveted voters in the country — francophone Quebecers living in ridings that could swing in any of two or even three directions.

On Friday, the Liberals said Trudeau would attend the debate being organized by TVA, the only major television network in the country not participating in the two debates — one in each official language — organized by the Leaders' Debate Commission, a body established by the government after the last election and chaired by former governor general David Johnston.

But Trudeau will not be participating in either of the two other proposed English-language debates — by Maclean's/Citytv and the Munk Debates. In 2015, the three major parties leaders participated in two debates in each official language and a fifth that was bilingual.

While an extra French debate provides another opportunity for Trudeau to call one of his opponents "mon amour," the decision also highlights how Quebec is central to the Liberals' re-election plans. But Trudeau isn't the only federal leader with Quebec on the mind.

Last week, Conservative Leader Andrew Scheer held a rally in Laval and gave a speech to the Chamber of Commerce of Metropolitan Montreal. On the weekend, NDP Leader Jagmeet Singh pledged he would increase Quebec's immigration funding if elected. And Yves-François Blanchet, leader of the Bloc Québécois, thinks of nothing else but the Quebec vote.

The Liberals, Conservatives and Bloc are circling the staggering NDP, hoping to gobble up the 16 seats the New Democrats won in the province in the last election. Outremont, where Tom Mulcair made history for the party when he won it in 2007, already fell to the Liberals in a byelection in February.

Where each party is best-positioned to make these gains differs — the Liberals on the island of Montreal, the Bloc in the surrounding suburbs and the Conservatives in the central part of the province. But where these areas intersect, there could be heated battles between two of the three parties and, in some case, all three.

That just happens to be where a lot of TVA's audience lives.

Parties need TVA audience

TVA is run by Quebecor, which also manages the Journal de Montréal and the Journal de Québec, and is headed by Pierre-Karl Péladeau — who was briefly leader of the Parti Québécois and who attended a Bloc Québécois campaign-launch event last month.

The network is the most-watched in Quebec and its audience trends more on the nationalist side of the political spectrum in the province, with big numbers among middle-aged French-speaking Quebecers and those living in the suburbs around Montreal.

This is a key demographic for the Liberals — as well as the Conservatives and the Bloc. It's an audience that the prime minister can't afford to shun.

The CBC's Canada Poll Tracker, an aggregation of all publicly available polling data, gives the Liberals a wide lead in Quebec with 35 per cent support, against 22 per cent for the Conservatives and 19 per cent for the Bloc.

The New Democrats, who captured just over 25 per cent of the vote in Quebec in 2015, are in a race for fourth with the Greens at 10 per cent apiece.

Three-way race outside of Montreal, Quebec City

But the Liberals' advantage on the island of Montreal and among anglophones inflates the party's numbers in Quebec. Outside of Montreal, the race is far more competitive.

Polling results provided to CBC News by Abacus Data from its latest survey suggest the Liberals are ahead of the Conservatives by about 20 points in Greater Montreal, but trail by a wider margin in the Quebec City region. Outside of the two big cities, the Liberals stand at just 29 per cent against 22 per cent for the Bloc and 17 per cent apiece for the Conservatives and NDP.

Léger shows a tighter race in the "regions," at 29 per cent for the Liberals, 26 per cent for the Conservatives and 22 per cent for the Bloc. Considering the larger margin for error of sub-regional samples in both polls, that is toss-up territory — a sharp contrast to the Liberals' lead in Montreal and the Conservative strength in Quebec City.

It puts a lot of ridings up for grabs, beyond just those that the New Democrats will be defending.

Liberals, Bloc contesting dozens of seats

The Poll Tracker's seat projection model suggests that there are a few legitimate three-way races between the Liberals, Conservatives and Bloc — seats like Drummond and Saint-Hyacinthe–Bagot in central Quebec.

There are a few Liberal-Conservative contests as well, like Québec and Louis-Hébert in Quebec City.

The biggest chunk of contested ridings, however, appear to be between the Liberals and the Bloc. The Liberals currently have the upper hand in these seats, but the model points to 24 ridings in which the two parties are considered to be in contention. The majority of them are in the suburbs around Montreal, with eight of them in the Laurentides region north of the city and another seven in the Montérégie to the south and east.

Bloc Québécois Leader Yves-François Blanchet is running in the riding of Beloeil–Chambly, one of 16 seats in Quebec the NDP won in 2015. (Justin Tang / Canadian Press)

With the numbers we can see at this stage of the race — and things will undoubtedly change — the Conservatives are playing on a smaller field. The Conservatives are seriously in the running in about 13 to 19 seats, whereas the range is nine to 22 seats for the Bloc and 39 to 55 for the Liberals.

High-risk, high-reward debate

All else being equal, a good performance by Trudeau in the TVA debate will help his party get closer to the top end of that range — a number the Liberals will need to approach if they want to secure another majority government.

But the risk is that if he has a bad performance, both the Bloc and Conservatives could be well-positioned to benefit, increasing the odds for the Conservatives to form government and the Bloc to re-acquire recognized party status in the House of Commons.

For Trudeau, attending the TVA debate is a high-risk, high-reward proposition. Scheduled for Oct. 2, it will take place before the French-language commission debate on Oct. 10, which might mitigate some of that risk since he will have one more opportunity to speak to francophone Quebecers.

But not attending would have been all risk, no reward. With the election shaping up to be close, that might not have been a gamble the prime minister could afford to take.