It's not yet clear what sort of impact (if any) Monday's English-language leaders debate will have on the outcome of the federal election.

Polls suggest NDP Leader Jagmeet Singh has the most potential for growth but if the NDP does get a boost from his debate performance, it could be some time before it shows up in Canadians' voting intentions.

The polls are much clearer, however, about who gained the most from last week's French-language TVA debate. That puts increased pressure on Yves-François Blanchet, leader of the Bloc Québécois, going into tonight's final debate of the campaign.

After more than four weeks, the polls are finally starting to shift in the CBC's Poll Tracker, an aggregation of all publicly available polling data. That is being driven primarily by Quebec, where the TVA debate has had a measurable impact.

Nationally, the Liberals and Conservatives are still in a close race, with the Liberals edging out the Conservatives at 33.9 to 33 per cent support. The Liberals also hold a seat advantage, thanks to leads in Ontario, Quebec and Atlantic Canada, and so are favoured by a margin of nearly two-to-one to win the most seats.

But the odds of anyone winning a majority government are looking slimmer, thanks to increases in support for the Bloc and, to a lesser extent, the NDP.

Check out the latest projections: CBC Poll Tracker

Polls conducted entirely or partially after the English-language debate aren't all showing the same trend lines. In general, though, it looks like both the Liberals and Conservatives have taken a hit, while the New Democrats and (marginally) Maxime Bernier's People's Party look to be in better shape.

But it is still early days — we don't have all the data yet. We might have to wait a little longer to draw any broad conclusions.

Singh boosted NDP prospects in English-language debate

We can say at this point that Singh has improved his party's prospects. Polling by Léger, Abacus Data and the Innovative Research Group (IRG) all pegged Singh as the winner of the debate among those who tuned in or heard about it (and the audience was significant — roughly 10 million Canadians).

According to Léger, Singh was cited as the winner by 29 per cent of viewers, followed by Conservative Leader Andrew Scheer at 22 per cent and Liberal Leader Justin Trudeau at 20 per cent. IRG found that Singh was the winner for 32 per cent of Canadians, followed by Scheer at 21 per cent and Trudeau at 13 per cent.

Abacus reports that 29 per cent said Singh did the most during the debate to earn their vote; both Trudeau and Scheer polled at 23 per cent on the same question. Only six per cent said Singh did the most to lose their vote, compared to 30 per cent for Trudeau and 35 per cent for Scheer.

All three polling firms also found that Singh — whether it was in terms of how he performed compared to expectations or whether people had a positive or negative reaction to his debate performance — impressed more people than he disappointed. It was quite the reverse for Scheer and Trudeau.

So the NDP's numbers will be worth watching over the coming days. The New Democrats already were looking somewhat better in the polls before the English-language debate. The early indications are that Singh has positioned his party to build on that momentum.

All eyes on Blanchet tonight

In Quebec, momentum for the Bloc Québécois has been building ever since last week's TVA debate. The polls suggest Blanchet was the big winner of that contest — which also had a significant audience in Quebec — and that the Bloc's support levels have increased as a result.

Among viewers of the TVA debate in Quebec, Léger found that 58 per cent chose Blanchet as the winner, followed at length by Trudeau at 20 per cent, Singh at 11 per cent and Scheer at just three per cent. According to IRG, Quebecers who watched or were aware of the debate chose Blanchet by a slimmer margin over Trudeau, at 34 per cent to 26 per cent.

Blanchet's strong performance and Scheer's bad showing have together contributed to a shift in voting intentions in the province.

Conservative leader Andrew Scheer gestures towards Liberal leader Justin Trudeau during the federal leaders debate in Gatineau, Que. on Monday, Oct. 7, 2019. (Sean Kilpatrick/The Canadian Press)

The Poll Tracker now shows the Liberals holding a lead in Quebec with 36 per cent support, followed by the Bloc at 25 per cent and the Conservatives at 18 per cent. Since the Oct. 2 update of the Poll Tracker, the day of the TVA debate, the Bloc has picked up four percentage points while the Conservatives have dropped three. Since the beginning of the campaign, the Bloc is up six points.

That changes the electoral math for the Conservatives and Liberals, increasing the odds that neither party can reach the 170 seats needed to form a majority government. It is especially complicated for the Liberals, who have dropped in the seat projection in Quebec because of inroads made by the Bloc, particularly in francophone regions of the province.

Léger finds that the Bloc now holds a 13-point lead over the Liberals among francophones. The Liberals still lead in and around Montreal and the Conservatives are ahead in Quebec City, but the Bloc is now 14 points ahead in the rest of Quebec, where the Liberals (and, to a lesser extent, the Conservatives) were banking on gains.

Trudeau, Scheer need to halt Bloc momentum

That changes the dynamics of tonight's French-language debate. Blanchet went relatively unchallenged in the English debate. Trudeau, meanwhile, was more focused on cutting the legs out from under Scheer on social issues — a strategy the polls suggest was largely effective. Scheer also was more keen on focusing on the Liberal leader, dismissing the Bloc as ineffective despite its "good intentions."

Scheer can't afford that kind of accommodation this time. His party needs a good performance tonight merely to save the seats it already holds in Quebec. Trudeau also needs to hit back at the Bloc to prevent his own numbers from slipping, particularly among francophones.

Singh needs to do well enough to secure a handful of seats in Quebec, such as those held by beleaguered NDP incumbents Alexandre Boulerice in Rosemont–La Petite-Patrie and Ruth Ellen Brosseau in Berthier–Maskinongé. In both seats, the NDP can't afford to lose votes to the Bloc.

That means the pressure will be on Blanchet. Expectations might have been low going into last week. Now they will be sky-high. If he disappoints, the Bloc's balloon might burst.