Floor-crossing has always been a feature of Canadian politics dating back to the first Parliament — and seeing four opposition MPs jump ship to join the government in a matter of months is rare but not unprecedented.
Prime Minister Mark Carney has only been in office for a year and is ranking near the top in terms of prime ministers who have had opposition MPs join his caucus during a parliamentary session.
John A. Macdonald, Robert Borden and Jean Chrétien attracted a swath of MPs to their respective governments — though all in vastly different circumstances.
Using information from the Library of Parliament, CBC News compiled a list of MPs who have changed political affiliation to join a governing caucus since Confederation. MPs who left politics to return and run under a different party and MPs who left a governing caucus in protest only to rejoin later were excluded.
Macdonald holds the distinction for welcoming the most MPs into his government during a session. Nine opposition members crossed the floor to sit in Canada’s first prime minister’s caucus — five of whom crossed on the same day in 1869.
But Macdonald benefited from unique circumstances that don’t neatly compare to Carney’s situation.
Every floor-crosser that joined Macdonald’s government came from the Anti-Confederation Party — a coalition of MPs mostly from the East Coast that sought to undo the formation of the Dominion of Canada.
That party collapsed during the first Parliament and its MPs largely dispersed between Macdonald’s Conservatives and the Liberals. Anti-Confederation Leader Joseph Howe himself joined the governing caucus in April 1969.
Robert Borden, who served as prime minister during the First World War, got a total of 17 MPs to join his ranks — though only one crossed the floor in the middle of a parliamentary session.
Sixteen sitting Liberal MPs ran and were elected with Borden’s Unionist government in the 1917 election which was almost exclusively contested on the conscription issue.
Borden and his pro-conscription slate won — but after the war, several MPs returned to the Liberals while others stayed with the Conservatives.
Chrétien is a more modern equivalent to Carney’s current context, though not perfectly comparable.
During his decade in office, eight MPs from the opposition benches joined Chrétien’s government.
Like Carney, Chrétien also attracted MPs from multiple parties, including: the NDP, the Progressive Conservatives, the Bloc Québécois and even the Canadian Alliance (formerly the Reform Party).
And while Carney nabbed four MPs in a span of four months, Chrétien scooped up an equal amount in much shorter order.
Four MPs — one NDP, two Progressive Conservatives and one Independent who had left the Progressive Conservatives a few months prior — joined Chrétien’s Liberals in less than a month in September and October 2000.
Chrétien mostly governed during a time where the right-of-centre vote was split between the Progressive Conservatives and Reform/Canadian Alliance parties.
And unlike Carney, Chrétien didn’t need floor-crossers to cobble together a majority government.
Carney isn’t the first prime minister with a minority to benefit from an MP defecting. Paul Martin, Stephen Harper and Justin Trudeau all welcomed opposition MPs into their ranks during minority Parliaments.
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The Harper and Martin governments benefited from two of the more contentious floor-crossings in recent memory.
Belinda Stronach joined Martin’s Liberals in 2005 while ending her relationship with Conservative Peter MacKay in the process. Her defection allowed Martin’s minority government to hang on for a few more months before they were ultimately defeated.
David Emerson switched parties and joined Harper’s cabinet shortly after the 2006 election, sparking an ethics investigation that ultimately cleared the MP of any wrongdoing.
But no prime minister has relied on floor-crossing to reach majority status. Carney could be the first with wins in two out of three byelections next month — two of which are being contested in safe Liberal ridings.
