From start to finish, the polls have shown Justin Trudeau's Liberals and Andrew Scheer's Conservatives in a close race, with no party opening up a significant gap over the other.

But in the end, there will only be one winner. Well, maybe. Probably.

After six weeks, the Liberals and the Conservatives remain pretty much where they started this campaign — deadlocked with roughly equal levels of support nationwide. The only thing they have accomplished over the last 39 days is to make their electoral positions worse.

(The Poll Tracker's polling averages and seat projections will be updated throughout the day and night until voting begins. Check the latest numbers here.)

At the outset, both parties had enough support that a majority government was not an unlikely outcome. A little momentum, a few beneficial vote splits and maybe a small error in the polls would have been enough to put either party over the 170-seat threshold required for a majority government.

But with gains by both Jagmeet Singh's New Democrats and the Bloc Québécois under Yves-François Blanchet, the prospects for a majority government of any political persuasion look much slimmer — and Scheer might have put his party entirely out of the running for one, according to the Poll Tracker's estimates.

Trudeau's Liberals could potentially still get there. But they need the stars to align far more perfectly than was the case six weeks ago.

Stumbling front-runners

On Day 1 of the campaign, the Poll Tracker had the Liberals and Conservatives tied at 33.8 per cent apiece. That set the tone for the duration — the largest lead the Conservatives ever held up to yesterday was 1.8 percentage points, while the biggest Liberal advantage was just 0.9 points.

And because of the weakness of the NDP and Bloc, the two leading parties had reasonable hopes for a majority government. The Liberals were pegged to be just a few seats shy of 170 when the campaign began.

The Liberals and Conservatives are well below that number now. The two parties have dropped a couple percentage points during the course of the campaign, an unusual situation in which both of the parties with the best chance of forming government have become more unpopular. At this stage, at least one of the leading parties usually has some positive momentum.

Instead, with Scheer and Trudeau boasting equally awful personal approval ratings, both seem to be stumbling as the finish line approaches.

The slide has been steepest for the Liberals in Quebec and British Columbia, while the Conservatives have taken their biggest hit in Quebec and Atlantic Canada. Both Trudeau and Scheer were counting on significant gains in Quebec as part of their formula for a majority government.

The rise of the Bloc is the main reason that formula doesn't seem to be working.

Bloc, NDP momentum

Since the party's 2011 electoral catastrophe, the Bloc has had a rotating cast of interim and (temporarily) permanent leaders. Blanchet was only installed in the job in January. At that point, the future of the party wasn't looking particularly bright.

But with his skilful use of issues like Bill 21 and pipelines and following strong performances in the two French-language debates, the Bloc looks like it is back. The party has been projected to win more than 30 seats since the last of those two debates and could very well win the most seats in Quebec.

The Bloc has gained more than 10 points in the province since the beginning of the campaign, by far the biggest increase in support any party has experienced anywhere in the country.

Blanchet isn't the only leader who has used this campaign to improve his party's fortunes. While Scheer and Trudeau attacked one another and Elizabeth May of the Greens got distracted by early controversies, Singh has run a generally smooth campaign. He punctuated that with a good performance of his own in the English-language debate that featured all six major party leaders.

After polls suggested NDP Leader Jagmeet Singh won the English-language debate, support for his party has risen. (Nathan Denette/The Canadian Press)

Since then, the NDP has gained about five points nationwide, putting up better numbers throughout Canada. The New Democrats have seen the biggest gains on two coasts and are now poised to pick up seats in places like B.C., Ontario and Atlantic Canada — gains that could make up for many of the losses the party is still likely to suffer in Quebec.

The NDP has seen its numbers improve in Quebec and now has some prospects of re-electing a few of its incumbents. But the rise of the Bloc has an impact on the NDP as well as on the Liberals and Conservatives — in the Quebec seats the NDP has the best hopes of winning, it's the Bloc that is now its biggest rival.

Decisive votes in Quebec, GTA and Lower Mainland

Regardless of the shifts we've seen since the beginning of the campaign, the election-deciding battlegrounds are the same: francophone Quebec, the Greater Toronto Area (GTA) and B.C.'s Lower Mainland.

The Bloc is well-positioned to make significant gains in the francophone regions of Quebec. A poll by Léger for TVA found the Bloc holding a decisive 15-point lead over the Liberals among French-speaking voters in the province. That could translate into many seats, particularly as Léger finds the Bloc holding significant leads in central Quebec and the suburbs around the island of Montreal.

Polls suggest that the Bloc Québéois under Yves-François Blanchet is the top choice of francophones in Quebec. (Graham Hughes/The Canadian Press )

Even in the Quebec City region, the traditional stronghold of the Conservatives in the province, the Bloc is challenging the incumbents. Scheer has not helped his party's fortunes in Quebec, with Léger finding Scheer in third among Quebecers' choice for prime minister, trailing the second-place Singh by four points.

Scheer had a 13-point lead over the NDP leader for second spot at the end of August.

The GTA — which, including Toronto itself, has more seats than eight of 10 provinces — remains the decisive battleground. The Conservatives could struggle to make the gains they need in the region, with some polls showing the Liberals retaining a sizeable edge both inside and outside Toronto.

Even in the polls that show a closer contest, the region looks split — which is a sure sign of a minority government if neither the Conservatives or Liberals are able to pull off a near sweep.

The Lower Mainland is also looking tight. Surveys show a three-way race in and around Vancouver, suggesting some hotly contested battles between the Liberals and New Democrats in Vancouver proper, with the Conservatives pressing in on the Liberals in the suburban seats they won along the Fraser River in 2015.

If the Liberals can do better than expected in all three of these battlegrounds, a plurality is virtually guaranteed and a majority is possible. But it's the Bloc in Quebec that may prove to be the biggest obstacle in pulling that off.

An uncertain outcome

There are still a lot of unknowns heading into tomorrow's election. The late campaign momentum for the NDP and the Bloc makes it hard to predict what will happen over the final weekend.

For the New Democrats, a number of polls published Friday and Saturday hinted that the party might have hit its ceiling in support. It might be even dropping back a little.

The numbers were less clear on whether the Bloc is running out of steam or continuing to move forward.

There is still a lot of potential for an unexpected outcome. The Poll Tracker has wide seat projection ranges for a reason — voters are hard to predict, and it doesn't require a big difference between the final polls and the final results for the seat breakdown to look very different. Over the last few elections, the average of the polls has always been within three percentage points of the result for any party. But in a tight race, three percentage points is huge.

No party has ever won a majority of seats in the House of Commons with less than 38.5 per cent of the popular vote. If it is to happen tomorrow, it would require either a significant miss in the polls or a new historical record to be set. Neither can be ruled out, but that is what it will take.

So the odds heavily favour a minority government — with an edge to the Liberals emerging with the most seats. But the race has been a toss-up in the polls from Day 1. Why should it be any different in the only poll that counts?