This Saskatchewan-born politician made his name as a staunch Conservative and equally virulent opponent of Pierre Trudeau's Liberal government. So colleagues were stunned when, in 1977, he joined Trudeau's ranks and was immediately granted a role in cabinet. Horner said his defection was caused by party leader Joe Clark's refusal to protect his Alberta riding of Crowfoot. The riding didn't appreciate the gesture — they voted Horner out in the next election.
Bouchard, a one-time loyalist and friend of Conservative prime minister Brian Mulroney, sparked a unity crisis in 1990 when he stormed out of a cabinet meeting during constitutional wrangling aimed at gaining Quebec's signature on the Constitution. He went on to form the sovereigntist Bloc Quebecois, lead the 1995 referendum campaign that came within a hair of breaking up the country and eventually become premier of Quebec
David Price and Diane St-Jacques
David Price and Diane St-Jacques were Quebec Tories who bolted to the Liberals on the same day in September 2000. Their defections were seen as a body blow to both party leader Joe Clark, who had just regained a seat in the House of Commons, and to their own political fortunes. The latter prediction proved false — both went on to be re-elected as Liberals.
The Nova Scotia MP raised eyebrows in 2003 when he left the newly merged Conservative party to join the Liberals. He's gone on to have a successful career as a Grit, holding a cabinet position under Paul Martin and currently serving as finance critic to leader Justin Trudeau.
Martin came to Parliament Hill as a member of the Reform party in 1993 and, when it ultimately became part of the Canadian Alliance, made a bid for party leadership. In 2004, however, he crossed the floor to join the Liberals. He would win two more elections under the red banner and retired as a Liberal in 2011.
In May 2005, then-Conservative MP Belinda Stronach famously abandoned her party in exchange for a cabinet position under then-Liberal prime minister Paul Martin. Her defection allowed Martin's minority government to win a key non-confidence vote and stay afloat until 2006. The switch also caused a dramatic end to her romance with current Justice Minister Peter MacKay. Stronach went on to be re-elected as a Liberal before leaving Parliament in 2008.
Emerson was first elected as a Liberal in Vancouver Kingsway in 2004 and served as industry minister under former prime minister Paul Martin. In 2006, just weeks after being re-elected, he shocked colleagues and constituents in his largely left-leaning riding by crossing the floor to join Stephen Harper's Conservatives. He served as minister of international trade and then foreign affairs before leaving politics in 2008.
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