In the 2015 Canadian Federal election, with leader Tom Mulcair, the left-wing New Democratic Party of Canada fell from the unprecedented 2nd place finish it got in 2011 election under the late Jack Layton to 3rd. The centre-left Liberals got a majority government.
The result was a disappointment, but not the disaster some made it out to be. They still got the 3rd highest number of seats in NDP history and avoided the crushing 1993 defeat the last time the a Liberal wave came in to remove a Conservative government.
During the election many where unhappy with Mulcair moving the party to the centre on some issues while the Liberals under Justin Trudeau moved left. Mulcair pledged a balanced budget despite the economic hit Canada was suffering from the drop in oil prices, while the Liberals said there would be a $10 billion deficit in the first year (their budget ended up with a $30 billion deficit). This created the perception that the Liberals where to the left to the NDP allowing them to solidify the anti-Harper Conservative vote. The NDP lost all the seats in downtown Toronto where the core of the left in Canada currently resides.
In Canada during party conventions there is a vote by delegates to test the support for the current leader. The rules require they got 50% support or a leadership race is triggered, however under to informal “Clark rule” they are expect to get at least 70% support. (In 1983 Conservative leader Joe Clark got 66.9% support, resigned and ran again for leader but lost to Brian Mulroney.)
On Sunday in Edmonton party delegates voted 52% against Muclair, the worst result in the history of these votes among major parties (They have been many less popular leaders then Muclair, but they have always resigned first).
In my opinion has the election result had been as poor, but without the shift to the centre or the election resulted in holding the Liberals to a minority Muclair could have stayed on as leader. The delegates where also inspired by the success of Bernie Sanders to believe a leader who is truly representative of the left can succeed rather then the past where leaders constantly moved to the centre to try and reach power.
After the success of Bernie Sanders and UK Labour leader Jeremy Corbyn I expect such a leader will rise in the NDP.
The NDP leadership race will use single-transferable vote and probably on-line ballots among paid up members (The fee is as little as $5 for students, retired and the unemployed). Only about 1% of Canadians are party members. The party executive will decide the timeline. It may not be until next year. Muclair will stay on as interim leader.