2015 Wildrose Party leadership election
The 2015 Wildrose Party leadership election was triggered December 17, 2014, following the decision by leader Danielle Smith and eight other MLAs to leave the Wildrose Party and cross the floor to join the ruling Progressive Conservative Association of Alberta (PCs). The party announced the next day that it would appoint an interim leader and hold an election to choose a permanent leader in 2015.
Source: Wikipedia — 2015 Wildrose Party leadership election (CC BY-SA 4.0)