On the first day of the Ontario election campaign, the race was Doug Ford's to lose. On the last day of the campaign, it remains the PC leader's race to lose — and he might just avoid doing that.

With less than 24 hours to go before the polls open and voters begin casting their ballots, the opinion polls show that the Progressive Conservatives are holding on to their slim lead over Andrea Horwath's New Democrats. And because of how the vote is projected to break down across the province, that likely is enough to give the PCs a majority government.

But it isn't a sure bet. A number of factors could conspire to prevent the PCs from attaining the 63 seats needed to form a majority government. The odds of that happening are low, but this has been a campaign full of surprises.

As of the morning of June 6, the CBC Poll Tracker — an aggregation of all publicly available polling data — suggests the PCs have about 38 per cent support. That's just enough to keep them ahead of the New Democrats, who stand at 36.5 per cent.

(The Poll Tracker will be updated with the final polls of the campaign as they are published — see here for the latest numbers.)

It's a far closer race than when the campaign began. The margin between the PCs and the New Democrats has shrunk by 13 points, as the PCs have dropped three points in the Poll Tracker over the course of the campaign while the NDP has soared by 10.

Recent Forum and Pollara polls have found that Doug Ford's unfavourable ratings with voters approach those of Kathleen Wynne. (Geoff Robins/Canadian Press)

The New Democrats were able to take some support away from the PCs, but the bulk of their gains came from the Liberals. At 19.1 per cent, Kathleen Wynne's party has plummeted seven points to what would be the worst performance in the party's history if the numbers are replicated when the votes are tabulated Thursday night.

The Greens have held steady at five per cent, but leader Mike Schreiner could make history himself by pulling off an upset in the riding of Guelph.

But this portrait has been in freeze-frame for two weeks now; since the May 24 update of the Poll Tracker, the PCs and NDP have been within two points of one another without exception.

The polls have been very consistent on this score, with no disagreements that cannot be explained away by normal sampling errors. It looks like a close race. Still, it might not turn out that way when the votes are turned into seats.

PCs favoured in number that counts

The Poll Tracker seat projection currently estimates that the most likely outcome for the PCs is 73 seats, well over the threshold for a majority government. Taking into account past polling errors and the imprecision of the seat projection model, the PCs could win between 54 and 86 seats — a range that is comfortable for the PCs and their majority prospects, but not a certainty.

More Ontarians had a positive view of the NDP's Horwath than a negative one, according to Forum and Pollara polls. (Galit Rodan/Canadian Press)

The New Democrats are projected to win between 38 and 63 seats, with 50 seats being the best guess. That gives them some overlap with the PCs, but requires that current polls overestimate PC support significantly, with virtually all of that error going in the NDP's direction rather than toward the Liberals.

Wynne has admitted already she won't be winning the election. But she does need to ensure her party reaches the bar of eight seats to retain official party status. The seat projection model thinks the Liberals could win as many as 11 seats — and as few as zero.

With the current likeliest outcome for the Liberals being one seat, that suggests the odds are better than not that the party will fall short of eight seats.

But all politics being local — and Wynne's admission included a plea for voters to elect Liberal MPPs in some ridings — there is the potential for the Liberals to out-perform expectations in a few seats.

NDP vote looks inefficient, but is it?

That the PCs are able to win many more seats than the NDP with only slightly more votes is due to the relative inefficiency of the NDP's support and the manner in which the first-past-the-post electoral system can reward a party that has even a modest lead in the popular vote.

The PCs are ahead in eastern Ontario and in the GTA-Hamilton-Niagara region, two regions that could get the PCs most of the way to a majority government on their own. The party could win more than two-thirds of the seats in the GTA-Hamilton-Niagara region with just 40 per cent of the vote, despite being barely ahead of the NDP. It could win three-quarters of the seats in eastern Ontario with the same 40 per cent vote share.

The New Democrats lead in Toronto and are narrowly ahead in southwestern Ontario, but are poised to win about as many seats as the PCs in these two parts of the province.

Wynne's party faces what would be the worst performance in its history if poll numbers are replicated in voting Thursday. (Andrew Ryan/Canadian Press)

Only in northern Ontario might the NDP's vote be efficient — delivering as much as 85 per cent of the region's seats with just 45 per cent of the vote. It doesn't help much, however, as there are only 13 seats in northern Ontario.

For this reason, the Poll Tracker estimates that the PCs have an 87 per cent chance of winning a majority government with these levels of support, with the NDP's chances being just six per cent. The odds of a minority government — about seven per cent — are low due to the Liberals not winning enough seats to make a minority government mathematically likely.

But changing turnout patterns could turn the projections on their head, making the NDP vote more efficient and the seat gap narrower than expected. The NDP's historic rise in the polls makes this possible if voters come out in unpredictable places. But how likely is that?

Turnout could favour PCs, but …

Polls suggest that the PCs are more likely to benefit from the turnout than the New Democrats. A poll by Léger has found that the PCs hold a six-point edge among voters 55 and older, a cohort that traditionally votes in large numbers. The same poll found the NDP ahead by four points among voters between the ages of 18 and 34, a group that has low turnout rates.

Both Pollara and Abacus Data found the PCs leading among votes already cast, with the PCs ahead by seven and four points, respectively, among Ontarians who voted in the advance polls. Those are ballots already in the system and counted, rather than hypothetical future votes that have yet to be cast.

But in the last provincial election in 2014, pollsters experimented with turnout models in an effort to avoid a repeat of the polling miss in British Columbia the previous year. And in every single case, the likely voter models did worse than a standard weighting to the general population.

Turnout was supposed to benefit the Ontario PCs in 2014 and give Tim Hudak a chance of winning. Instead, the PCs under-performed their polls and the Liberals won a majority government.

Events and undecideds

The roller coaster final days of the campaign have also injected a degree of uncertainty. Wynne's admission of defeat and plea for the election of enough Liberal MPPs to keep the PCs or the NDP to a minority government hasn't had an impact on the polls, but it could have an influence on local races.

Recently, Renata Ford — widow of Doug Ford's late brother Rob — went public with a lawsuit claiming a lack of support for her bereaved family and bad management of the family firm under Doug Ford. The allegations — which have not been proven in court, and which Ford denies — could undermine the PC leader's already waning popularity.

Forum and Pollara have recently found Ford's unfavourables approaching those of Wynne. Forum put the number of Ontarians disapproving of Ford at 55 per cent, just 10 points below Wynne's score, while Pollara also found 55 per cent of respondents reporting negative views of Ford — just three points below Wynne.

Significant portion undecided

In both polls, more Ontarians had a positive view of the NDP's leader than a negative one.

There is also a significant portion of the electorate that remains undecided, ranging as low as six to seven per cent (Léger and Mainstreet, respectively) and as high as 12 to 14 per cent (Pollara and Abacus). If those undecideds swing disproportionately to the NDP or the PCs, it could have a big impact on a close race.

Nevertheless, Doug Ford and the PCs retain significant advantages and are the favourites to secure a majority government going into election day, a position they have never given up from Day 1.

But keeping an eye on the final polls of the campaign is still a good idea — electoral law in Ontario allows for the reporting of new opinion surveys up until Wednesday night. Over the past four weeks, the Ontario election campaign has been full of surprises and has changed quickly. There's no reason it should be any different in the last 36 hours.