Brantford—Brant South
Federal by-election in Ontario on December 7, 2026, after the departure of Larry Brock (Conservative).
The Liberal Party is the favourite, with a 86% chance of winning and 48% of the projected vote.
The forecast
| Party | Projected share | Range (80%) | Chance of winning |
|---|---|---|---|
| Liberal | 48.3% | | 86% |
| Conservative | 41.6% | | 14% |
| NDP | 3.8% | | <1% |
| People's Party | 3.2% | | <1% |
| Green | 3.2% | | <1% |
Our general-election projection for the riding still has the Conservatives ahead; the by-election forecast does not. The difference is turnout. In a general election most voters show up; in a by-election, the side whose supporters are less motivated loses more of them. Liberal seats paid that price in 2024. With the Conservatives down nationally, their seats pay it now. A 3-point personal-vote correction for Brock is enough for the seat to change hands.
What the forecast adjusts
- Personal vote removed
- 3 points removed from the Conservative vote: the share that went to Larry Brock rather than to the party. 41.5% → 38.5%
- By-election turnout
- At the April 13, 2026 by-elections, for the same national shift, the Conservative vote fell about 3 points further and the Liberal vote rose by as much: opposition voters turn out less than government voters. Conservative −2.8 · Liberal +3.1
The 2025 result
The race
The Conservatives held this seat by eleven points in 2025. Brock took little of that with him. What changed is the national picture: the Conservative vote is down about nine points since April 2025, and turnout at this year’s by-elections has worked against the opposition.
- Larry Brock announced his resignation on August 6, 2026; the seat has been vacant since September 18. He returned to the Crown attorney’s office in Brantford.
- He is the seventh MP to leave the Conservative caucus since the 2025 election. Four of them joined the Liberals.
- Conservative share compared with the party’s Ontario-wide vote: +5.8 points in 2015 and +7.2 in 2019, both before Brock was elected. Little of the edge is personal.
The other by-elections on December 7, 2026
| Riding | Favourite | Chance of winning |
|---|---|---|
| Rosemont—La Petite-PatrieQuebec | Liberal | 95% |
| Saint-Hyacinthe—Bagot—ActonQuebec | Bloc Québécois | 72% |
| Laurier—Sainte-MarieQuebec | Liberal | >99% |
| Yorkton—MelvilleSaskatchewan | Conservative | >99% |
| Scarborough NorthOntario | Liberal | >99% |