Liberals have a 3-to-1 spending advantage in a majority-deciding by-election

The spending rules behind Terrebonne’s rematch - and what they mean for control of the House

Canadian politics rarely turns on a single riding. This time, it might.

With Edmonton MP Matt Jeneroux crossing the floor to join Mark Carney’s Liberals, the government now sits at 169 seats. In a 343-seat House of Commons, 172 is the majority threshold. There are three vacancies. Two - University—Rosedale and Scarborough Southwest - are Liberal strongholds and, barring an upset of historic proportions, will remain so. That would bring the government to 171.

Which leaves Terrebonne.

In the 2025 general election, the Liberal candidate “won” Terrebonne by exactly one vote. The Supreme Court nullified the result due to a mail-in ballot error, sending the riding back to the electorate. If the Liberals win the rematch, they secure a majority government. If they lose, they remain in minority territory.

This may be the most extraordinary by-election in modern Canadian history.

But this contest is not occurring on a level playing field.

It’s financially tilted.

The spending imbalance few know about

Under the Canada Elections Act, local campaigns have their own riding-level spending caps. Those local campaign limits are separate from the national party’s by-election spending limit. When multiple by-elections occur at the same time, however, the national spending ceiling is calculated across all of them. That money can be spent anywhere.

There are three by-elections that will happen at the same time.

For the Liberals, Conservatives and NDP, that means a national cap tied to three ridings. In practice, the Liberals have little need to allocate resources to the two safe Toronto contests and can concentrate virtually all of its allowable national spending in Terrebonne.

The Bloc Québécois cannot do the same. Because it runs candidates only in Quebec, its “national” spending limit is effectively tied to a single riding - unless it makes the unusual decision to field candidates outside Quebec solely to expand its cap.

The result is a major structural advantage: the Liberals are operating with a three-riding national spending allowance in a single decisive race, while the Bloc works within the confines of one.

In a riding decided by one vote, that matters.

By-elections are won through organization, persuasive mail, voter identification, digital targeting, and turnout operations. All of those require resources. Money alone doesn’t determine outcomes - but financial flexibility shapes the battlefield in subtle and important ways.

The Liberals can deploy roughly three times the national resources the Bloc can.

Based on 2025 elector counts, the national party spending limit for a typical riding of roughly 90,000 electors is approximately $110,000 to $115,000. With three by-elections occurring at once, the Liberal national cap is therefore in the range of $330,000 to $345,000. If the Bloc contests only Terrebonne, its effective national limit remains roughly $110,000.

Local candidate spending limits in Terrebonne are approximately $150,000 per campaign and apply equally to all candidates. The imbalance exists at the national level.

That advantage matters because of what this race could decide.

At present, the Liberals govern with constraints. Opposition parties hold the majority in the House, and the Conservatives and the BQ combined hold a majority in committees. They can compel documents, summon witnesses, and use procedure to sustain uncomfortable political pressure.

A majority wipes all of that away.

With 172 seats, Mark Carney could prorogue Parliament, return with a new Speech from the Throne the next day, and reconstitute committees with the Liberals now having a majority of seats around the table. Files that currently generate friction could be managed quietly through procedure rather than prolonged public hearings.

That is not a symbolic shift. It’s operational control of the House.

Terrebonne, therefore, isn’t simply a Quebec rematch. It’s the hinge on which a majority government may turn.

The strategic compression

When the stakes become this clear, the ballot question inevitably narrows.

Do you want a Liberal majority - or not?

In most by-elections, smaller-party support compresses because voters are not choosing a government. In this case, the compression may be even sharper, because the question is unusually simple: majority or minority. Conservative voters in Terrebonne know their path to victory is narrow. NDP voters face a worse reality, despite holding the seat in 2011. Both parties must decide whether their priority is partisan expression or preventing a particular national outcome.

For the Bloc, the challenge is existential. Its brand has long been built around denying Ottawa unchecked authority. If it can’t frame this contest as a firewall against majority control, it risks watching soft support drift elsewhere - and a loss would also have implications for the Bloc’s provincial counterpart, the Parti Québécois, which not long ago appeared destined to form government but now finds itself in a tightening contest with the CAQ.

Quebec voters are highly attuned to leverage. That dynamic will shape turnout and tactical voting decisions in the weeks ahead.

A riding built for volatility

Terrebonne has a history of political upheaval. It was a Bloc stronghold for two decades before the 2011 Orange Wave delivered it to the NDP. The Liberals have steadily advanced since, culminating in last year’s one-vote result.

Province-wide polling now suggests the Liberals hold momentum in Quebec. But by-elections often defy broad polling trends. They are local, emotional, and turnout-driven.

And when the previous margin was one vote, incremental advantages matter - organizational, narrative, and financial.

Especially financial.

The bottom line

Most Canadians will focus on the one-vote margin and the drama of a rematch. Inside campaigns, the conversation is different.

This is a structurally imbalanced fight that could determine whether Canada has a majority government.

If the Liberals win Terrebonne, Mark Carney secures the 172 seats required for majority status and dramatically strengthens his hand for the next three years. If they lose, Parliament remains balanced and opposition parties retain meaningful leverage.

One riding will decide which version of Ottawa Canadians wake up to.

And it will do so in a contest shaped not only by a single ballot - but by a three-to-one national spending advantage.

Unless, of course, another MP crosses the floor.

Because in a Parliament this close to the threshold, one defection (or by-election) changes everything.