338 Sunday Update: Liberals Hold Majority After By-Election Sweep

By-election results and recent polling suggest little momentum for Pierre Poilievre’s CPC.

🍁Good morning, dear 338Canada readers,

The federal Liberals swept last Monday’s by-elections to climb to 174 seats in the House of Commons — two seats clear of the threshold for a majority.

My podcast partner Eric Grenier and I streamed the results on Monday night, and while the two Toronto ridings were decided early in the count, it was only past midnight, and with over 98% of ballot boxes counted, that we were able to declare the Liberals victorious in Terrebonne, in suburban Montreal.

While they were not projected as competitive in any of the three contested ridings, the Conservatives saw their share of the vote fall by double digits in all three — this is especially notable since Conservative voters historically tend to show up in by-elections, even in unfavourable ridings for the CPC.

The importance of by-elections is sometimes overblown in political analysis, so we must be careful not to draw hasty conclusions from what were three local events. However, had the Conservatives grown their share of the vote by, say, 10 points — even in a losing effort — we would assuredly point it out.

Imagine a near-tie between the Liberals and Bloc in Terrebonne, but with a vote share of 28% for the Conservatives (compared to 18% in the 2025 election). Our conclusions would be that Poilievre’s CPC has gained strength in suburban Montreal. (Instead, the CPC vote collapsed to a measly 3% in Terrebonne.)

Ditto in the two Toronto ridings. In Scarborough Southwest, the Conservatives took almost 31% of the vote in 2025. On Monday, the CPC candidate received just under 19% — a drop of 12 points. Had the Conservative vote grown by 12 points instead, from 31% to 43%, the Liberals would still have won, but our analysis of the current landscape would be wildly different — and rightly so.

So let’s not overblow the importance of these by-elections, but let’s not completely dismiss them either. They measured a snapshot of local voters’ preferences and enthusiasm — neither of which were favourable to the Conservatives, no more, no less. More broadly, these results do not suggest a party building momentum since Poilievre’s leadership review in January — quite the opposite.

Let’s now recap the past week in the polls and update the 338Canada federal projections. Welcome to the 338 Sunday Update.

📊 Enjoy independent, data-driven analysis?
🍁 Join thousands of readers supporting 338Canada by subscribing here.