Aitchison Exit Adds to Conservative Vacancies as Caucus Attrition Continues

Conservative MP Scott Aitchison will resign his Parry Sound-Muskoka seat by the end of the year, sources told The Globe and Mail.

Aitchison informed Conservative Leader Pierre Poilievre of the decision last week. He told Poilievre last week. The news was first reported by CTV, with CBC News reporting separately, citing three sources, that Aitchison is expected to resign later this fall.

Aitchison holds the housing critic portfolio in Poilievre's shadow cabinet and represents Parry Sound-Muskoka, a federal constituency in Ontario. House of Commons records list him as a Conservative member in the 45th Parliament, with his current term beginning April 28, 2025. He has represented the riding since 2019 and won re-election in 2025 with 52.2 per cent of the vote. He has been in politics since 1994.

Aitchison ran against Poilievre for the Conservative leadership in 2022 and finished fifth. Two sources characterized his decision to leave as a desire to try something else beyond elected life. CTV News reported, citing a source close to Aitchison, that the resignation will come by the end of the year.

The departure will create yet another vacancy on Poilievre's benches, sources say. CTV News' Front Bench panel characterized the resignation as "a real body blow" for Poilievre.

The attrition is now sustained. Conservative MP Larry Brock officially resigned his seat in Brantford-Brant South earlier this month after announcing this summer he was stepping down. Saskatchewan MP Cathay Wagantall resigned her seat on Aug. 31 after announcing in June she was leaving. Four Conservative MPs have crossed the floor to the Liberals since last November. Quebec MP Richard Martel resigned his seat for a Senate appointment and the Conservatives lost his riding in the August byelection.

The arithmetic is tight for the Conservatives even before Aitchison's seat empties. The Liberals hold 173 seats for a majority government while the Conservatives hold 137 seats including Aitchison, with six vacancies. Nanos Research polling cited puts Liberal support at 49.9 per cent and Conservative support at 27.9 per cent.

The broader context here is caucus management under minority-turned-majority pressure, and it helps explain why a single Ontario resignation carries weight beyond its byelection. For party operatives, the issue is not only the writ in Parry Sound-Muskoka. It is the pattern of exits and crossings that forces a leader to fill critic slots, defend safe seats, and keep remaining MPs focused on Parliament rather than personnel. A housing critic matters in that calculation because housing remains a shared-jurisdiction file where Ottawa sets fiscal and mortgage parameters while provinces and municipalities control supply, approvals and tenancy.

Looking at what this means for Poilievre, the near-term questions are procedural and practical. A vacancy triggers a byelection call on the government's timeline, leaving a critic post to cover and a riding association to revive. The longer question is retention. When departures accumulate across regions, from southern Ontario to Saskatchewan to Quebec, whips and House leaders watch attendance, committee assignments and candidate recruitment more closely. That dynamic, rather than any one resignation, will shape Conservative positioning heading into the next sitting.