Two years after being sworn in with a majority government, the Liberals under Prime Minister Justin Trudeau would have less than even odds in retaining that majority if an election were held today.

But despite the reduced lead they hold over the Conservatives in the polls, the Liberals are still in a strong position thanks in large part to Quebec, where the New Democrats' falling support gives Trudeau the opportunity to make up for losses in the rest of the country.

Five national polls were published over the last week, all ending their interviews between Oct. 23 and 27. Their results showed a Liberal lead over Andrew Scheer's Conservatives ranging from two to 12 percentage points.

While that appears to be contradictory on the surface, the results are consistent with a roughly six point gap between the two parties, considering the margin of error of each individual poll.

The Liberal lead is slipping, says CBC polls analyst Eric Grenier. 3:58

Accordingly, the CBC Poll Tracker, which aggregates all polling data on voter intentions, shows the Liberals ahead by 5.8 points, awarding them 37.4 per cent to 31.6 per cent for the Conservatives. The New Democrats trail in third at 17.9 per cent. The Greens and Bloc Québécois follow with 6.1 per cent and 4.8 per cent, respectively.

Compared to the 2015 election, this puts the Liberals down 2.1 points, the Conservatives down 0.3 points and the New Democrats down 1.8 points. The Greens (+2.7) and other parties (+1.3) are over-performing their electoral performance.

Conservative Leader Andrew Scheer rises during question period in the House of Commons on Oct. 25. (Adrian Wyld/Canadian Press)

The Greens routinely poll higher than the support they have received at the ballot box, while the "others" can be a parking spot for undecided or disinterested voters. So the drop in support for the major parties, at least at the national level, may be less significant than it appears.

But there are large variations at the regional level which point to very real movement in public support — as well as a potential majority path for Trudeau.

Coin-flip odds for a majority

As recently as mid-September, the polls put the Liberals in a position that would virtually guarantee them a majority government. The Poll Tracker — which runs simulations of electoral outcomes based on where the parties stand in the polls — put the probability of a Liberal majority government as high as 93 per cent on Sept. 8.

But that position has deteriorated. The latest projections put the probability of a Liberal majority if an election were held today at just 47 per cent. This means that the chances of a re-elected Liberal majority would be about the same as a coin toss.

There would be a 44 per cent chance of a Liberal minority in a snap election — suggesting that the Liberals would still have a 91 per cent chance of winning the most seats — while the Conservatives would have a nine per cent chance of winning. That is down, however, from two weeks ago, when the model gave the Conservatives a 21.5 per cent chance of winning the most seats, or about one in five.

The average projection awards the Liberals 180 seats, well above the 169 needed to form a majority government. That's down just four seats from their performance in 2015. So how can the Liberals still be in a position to win a majority government — even at coin-flip odds — with just a 5.8-point lead over the Conservatives?

The reason is Quebec.

The Liberals' Quebec cushion

No party since 1930, before the emergence of the CCF and the establishment of a three (or more) party system, has won a majority government with a lead of less than 7.6 points over the second-place party (this was the Liberals' margin in 2015).

But while the projection model suggests the Liberals could lose 22 seats outside of Quebec based on current polling levels — thereby robbing them of their majority — they would make up for most of those losses with 17 seat gains in Quebec (and one in British Columbia).

Prime Minister Justin Trudeau, left, and the Liberals` winning candidate Richard Hébert in the Lac-Saint-Jean byelection. (Francis Vachon/Canadian Press)

The Liberals are leading in Quebec with 41.2 per cent, according to the Poll Tracker, up 5.5 points from their 2015 result in the province. But while they edged out the NDP in Quebec by little more than 10 points in 2015, the Liberals are currently up by more than 20 points over any of their rivals.

The Bloc Québécois is now in second at 20.8 per cent, followed by the NDP at 15.4 per cent and the Conservatives at 14.7 per cent.

That NDP score represents a 10-point drop, enough to put every one of the NDP's 16 seats in the province in danger. The trend line has not improved for the party with the selection of Jagmeet Singh as its new leader on Oct. 1.

The recent byelection result in Lac-Saint-Jean, in which the Liberals surged ahead to win a seat away from the Conservatives as the NDP's share of the vote plummeted, was a demonstration of Trudeau's potential to do very well in Quebec in 2019.

Shaky majority foundations

His majority might count on repeating his party's byelection success throughout Quebec, as the Liberals are down about two points in B.C. and Alberta and five points in Ontario and Atlantic Canada.

But the Liberals' theoretical gains in Quebec are built on a shaky foundation — more than half of them are projected to be won by five points or less. It would not take much variation in the polls to erase those Liberal seat wins and hand more ridings outside of Quebec to the Conservatives and NDP.

The Liberals recently moved up two promises — the small business tax cut and the indexing of the Canada Child Benefit — that had either been delayed or scheduled to occur in their second mandate. That this decision was made at the same time the polls put the possibility of that second majority mandate into question might not be a coincidence.