More than 300 MPs have crossed the floor in Parliament since Confederation

A recent Supreme Court ruling also cost the government a seat by overturning last spring’s election results in the Quebec riding of Terrebonne.

This is the third such blow to Conservative Leader Pierre Poilievre and his caucus in recent months. 

Jeneroux announced his resignation in early November, just days after Nova Scotia MP Chris d’Entremont left the Conservative caucus to join the Liberals.

Ontario MP Michael Ma became the second to defect from the Tory ranks to the Carney Liberals on Dec. 18.

Switching parties between elections — a practice known as floor crossing — is a controversial practice. Still, more than 300 members of Parliament have changed parties while in office since 1867.

The first known MP to cross the floor was Stewart Campbell, a Nova Scotian who, in 1868, left the Anti-Confederates for the Liberal-Conservatives under Sir John A. Macdonald. The Dictionary of Canadian Biography says Campbell was later pelted with eggs at a “social occasion.”

Library of Parliament data shows that over the last 25 years, about 80 MPs have changed their party affiliation between elections. Those switches often happened following a change in leadership, or sometimes following  a complete overhaul of the party itself.

In September 2000, Quebec MPs David Price and Diane St-Jacques left the Progressive Conservatives to join the Liberals, announcing their decision just after Joe Clark won a byelection to return to the House of Commons as the leader of the PCs. They said it was to prevent their seats from going to the Bloc Québécois.

Former Progressive Conservative MP André Harvey, who had left the party to sit as an Independent months earlier, also joined the Liberals later that month.

In 2003, days after the vote that merged the Progressive Conservative party with the Canadian Alliance to form the modern Conservative party, Progressive Conservative MP Scott Brison crossed the floor to the Liberals, saying the party better reflected his personal values.

Brison — Canada’s first openly gay federal cabinet minister — said he struggled with the merger and the fact that the PC party he grew up with no longer existed.

Belinda Stronach, who ran for the leadership of the new Conservative party in early 2004, crossed the floor to the Liberal party in 2005. She said that then-Conservative leader Stephen Harper wasn’t sensitive to the needs of all parts of the country.

In 2006, David Emerson jumped to the Conservative bench just two weeks after he won a federal election as a Liberal. Emerson accepted a role as a minister in Prime Minister Stephen Harper’s first cabinet. His move led to an inquiry by the Office of the Ethics Commissioner, which found that no rules were broken by either Emerson or Harper.

Leona Alleslev crossed the floor from the Liberals to join the Conservatives in 2018. Alleslev said the Liberal government had not adequately addressed some of the challenges facing Canada, citing its handling of the economy, tax reform, foreign affairs, trade and military spending.

In 2021, Fredericton MP Jenica Atwin left the Green Party to join the Liberals after winning the party’s first ever seat in Atlantic Canada. Atwin said at the time there were too many distractions in the Green Party and she wanted to work in a more supportive and collaborative environment.

Ontario MP Eve Adams crossed the floor to the Liberals in 2015. She said she no longer felt a part of the Conservative party, either “politically or intellectually.”

This report by The Canadian Press was first published Feb. 18, 2026. 

—With files from Kyle Duggan and David Baxter