Rosemont—La Petite-Patrie
Federal by-election in Quebec on December 7, 2026, after the departure of Alexandre Boulerice (NDP).
The Liberal Party is the favourite, with a 95% chance of winning and 36% of the projected vote.
The forecast
| Party | Projected share | Range (80%) | Chance of winning |
|---|---|---|---|
| Liberal | 35.9% | | 95% |
| Bloc Québécois | 23.9% | | 3% |
| NDP | 23.6% | | 2% |
| Conservative | 9.7% | | <1% |
| Green | 5.3% | | <1% |
| People's Party | 1.5% | | <1% |
We remove at most 18 points of personal vote from the NDP, less than half of Boulerice’s own 2025 result, and never take the party below 19%. The votes removed go mostly to the parties closest to the NDP (Liberals, Bloc, Greens), not in proportion to local strength, which would have handed the Conservatives votes they were unlikely to get.
What the forecast adjusts
- Personal vote removed
- 18 points removed from the NDP vote: the share that went to Alexandre Boulerice rather than to the party. 43.3% → 25.3% · floor 19%
The 2025 result
The race
Alexandre Boulerice was the last New Democrat elected in Quebec: 40.5% here in 2025, against 4.5% for his party across the province. He left to run for Québec solidaire. How much of that vote belonged to the NDP rather than to him decides this race.
- Boulerice sat as an independent from April 27, 2026 and ran for Québec solidaire in Gouin at the Quebec election of October 5, 2026. His seat has been vacant since August 25.
- Comparing 40.5% here with the NDP’s 4.5% across Quebec overstates his personal vote, because it puts central Montreal and the regions in the same average.
- Neighbouring ridings with similar profiles, and no well-known NDP candidate, gave the party 18.6% (Laurier—Sainte-Marie), 16.1% (Papineau) and 12.8% (Hochelaga—Rosemont-Est) in 2025.
- Québec solidaire won all four provincial ridings that overlap this one in 2022, including Gouin with 59.4%, its best result in Quebec. Those voters do not all vote NDP federally, but the left has a real base here.
- Without a correction, the general-election projection would still put the NDP near 44% here, a share that depends on a candidate who is not running.
The other by-elections on December 7, 2026
| Riding | Favourite | Chance of winning |
|---|---|---|
| Saint-Hyacinthe—Bagot—ActonQuebec | Bloc Québécois | 72% |
| Laurier—Sainte-MarieQuebec | Liberal | >99% |
| Yorkton—MelvilleSaskatchewan | Conservative | >99% |
| Brantford—Brant SouthOntario | Liberal | 86% |
| Scarborough NorthOntario | Liberal | >99% |