 The party would go on to lose a June 2014 by-election to the Liberals in the previously safe riding of Trinity-Spadina, which was made vacant following incumbent Olivia Chow's decision to run unsuccessfully in the 2014 Toronto mayoral election.By May 2015 however the NDP had managed to recover much of its lost ground in public opinion polling and was finding itself in a tight three-way race with both the Liberals and Conservatives.Commentators pegged several factors, including Mulcair's opposing stance against the Conservative's Bill C-51 which the Liberals agreed to support and the surprise win for the Alberta NDP in the 2015 Alberta provincial election, as having helped revive the federal party's lagging fortunes.