History. 4 of 5 by-elections in opposition seats: the seat stayed with the party that held it; once it went to another opposition party (Sherbrooke, 1998).
Hunch. The NDP won 41% here in April 2025 with Alexandre Boulerice, its MP since 2011, but on the same day it got only 18.8% next door in Laurier-Sainte-Marie, and he has since left for Quebec's National Assembly.
The Rosemont-La Petite-Patrie market resolves on Elections Canada's result for that seat on 7 December 2026: YES if the NDP candidate wins, NO if anyone else wins. The result counts when all polls have reported, or after a recount if one is held, with CBC News and The Globe and Mail as the backup.
We looked for cases where Canada filled an empty seat in parliament by a by-election while the government had a majority of ten seats or fewer, and had already taken a seat from the opposition at an earlier by-election in the same parliament. We found nine such by-elections, from 1998 to 2000, on five polling days under the same Liberal government.