By my count, there have been six MPs who have quit the caucus to which they were elected since Stephen Harper became prime minister in 2006.
Three Conservative MPs were involuntarily removed — i.e. kicked out — of the Conservative caucus since then. They would be Bill Casey, Garth Turner and Helena Guergis. Casey sat as an “independent Progressive Conservative.” Turner would join the Liberal caucus. Guergis sat as independent. Casey did not stand for re-election after leaving the Conservative caucus. Both Turner and Guergis subsequently lost their seats in the next general election. Peter Goldring voluntarily withdrew from the Conservative caucus and is sitting as a “Conservative Independent” while he fights a drunk driving charge.
Joe Comuzzi was a long-time Liberal MP and in 2007 defied his party and voted in favour of the Conservative budget — his riding was getting a hospital in that budget — and he was expelled from the Liberal caucus. He ended his parliamentary career as a Conservative MP but did not seek re-election as a Conservative.
So with those caveats, here’s the count:
The overall count (and again, this is since 2006):
- NDP have lost three.
- Liberal Party of Canada has lost four.
- Liberals have gained two.
- Bloc Quebecois has gained one.
- Green Party of Canada has gained one.
- Conservative Party of Canada has gained three.
- Three sat as independents after leaving their original caucus.
Here’s the others:
- Feb 6, 2006: David Emerson quits the Liberal caucus within days of the 2006 general election to become a Conservative MP and join Stephen Harper’s cabinet.
- Jan 5, 2007: Wajid Khan quits the Liberals and joins the Conservatives.
- Aug 30, 2008: With Liberal Blair Wilson facing expulsion from his caucus by then-leader Stephane Dion over Wilson’s financial irregularities, Wilson resigns from the Liberal caucus and declares his intention to sit as a Green Party MP. The House of Commons was on summer recess when he made that declaration and, before he could make history as the first Green to sit in the House, the 2008 general election was underway and he lost his seat.
- Jan. 10, 2012: Lise St. Denis quits the NDP to join the Liberals.
- April 23, 2012: After being disciplined by the NDP whip because he wanted to vote against his party’s wish on the gun registry — he wanted it dead — Hyer declares he will leave the NDP caucus and sit as an independent.
- Feb 28, 2013: Claude Patry leaves the NDP for the Bloc Quebecois.