The earliest example of an incumbent leader being challenged from the convention floor happened in 1973 when Douglas Campbell unsuccessfully opposed David Lewis' leadership.
[3] Then-leader Thomas Mulcair lost such a vote at the 2016 convention, resulting in the 2017 leadership election being called.
[4] In practice, all three CCF leaders had been chosen by their parliamentary caucus and then elected unanimously at a subsequent national convention.
The NDP held a series of regional and labour "caucus votes" prior to the national convention.
A fourth candidate, Herschel Hardin, participated in the regional caucuses but did not win sufficient delegate support to qualify for the convention.
[10] The party chose Thomas Mulcair as their new leader following the death of Jack Layton on August 22, 2011.
The results were announced on October 1 in Toronto, Ontario at the Westin Harbour Castle.