Tom Mulcair took over the NDP as it savoured the tantalizing prospect of forming the government for the first time but his party has instead suffered a brutal loss as he failed in his bid to be the champion of change.
The party that was the Official Opposition has shrunk to third place in the Commons under the leadership of the Quebec lawyer who held out the hope of victory. And no one in the party could have guessed how extensive the carnage would be.
The election night pain for the New Democrats started early, in Atlantic Canada, where star candidates and seasoned NDP veterans like Peter Stoffer and Megan Leslie handed their seats to Liberals. Ontario ridings also dropped away, taking other key members of Mr. Mulcair's caucus.
Full coverage of Federal Election 2015
But the most devastating losses took place in Quebec, where the New Democratic Party's massive Orange Crush of 2011 was almost washed away by Justin Trudeau. Mr. Mulcair was fighting for his own seat until late in the night. Quebeckers – in large numbers – turned their backs on the party they embraced when it was led by Jack Layton.
When Mr. Mulcair took the stage late Monday to concede his party's defeat, it would not have been a surprise to hear that he was stepping down as party leader. But he gave no indication that he intends to resign. Instead, he talked about the importance of his party, the country, and the need for New Democrats to work hard for Canadians in the new majority Liberal Parliament – and made no mention of the blow he has been dealt.
"With this election, Canadians have asked us all to work with them. We will not let them down," he told his cheering supporters. "I could not be more proud of the diversity and strength of our NDP team."
As recently as three weeks ago, the NDP was hoping to add to its seats in the House of Commons. Mr. Mulcair spent the campaign travelling to Conservative ridings with the intention of making gains at the expense of Tory incumbents. But the Conservatives instead fell to the Liberals, and so did Mr. Mulcair's New Democrats.
The results are a heavy blow to the top echelons of the NDP, most of whom were with Mr. Layton as he took the party from 37 seats in the 2008 election to 103 four years ago.
Mr. Mulcair has put on a brave face in the final days. But well before his campaign plane landed in Montreal on Sunday, party officials knew the election was lost.
Nevertheless, Karl Bélanger, Mr. Mulcair's principal secretary, said the party would find a way to insert NDP values into a Liberal agenda.
"We have a track record of working with the Parliament that has been elected by Canadians," he said. "We fight for the things we believe in but work with other parties where common agreement arises."
Mr. Mulcair, for instance, said during the campaign that, of all the promises in his 72-page platform document, his top priority would be to reset the relationship with Canada's First Nations. It is an aspiration shared by the Liberals and something upon which the two parties can find common ground.
But even though it is a short walk from the government benches in the House of Commons to those of the third party, the gap in the ability to realize a leader's vision for Canada is vast.
Mr. Mulcair told supporters at every stop of the long election campaign that New Democrats had never been so close to forming the government and realizing that vision. At the time the writ was dropped, that was true.
The NDP was leading in the polls, albeit by a small margin, and Mr. Mulcair seemed to have both the momentum and the gravitas needed to take his party to power for the first time in its more than 50-year history. He refused to take questions from reporters on the first day of the campaign in a move calculated to demonstrate his position as front-runner.
But he didn't stay there for long. For the first seven weeks after the election was called, there was a tight three-way battle with both the Conservatives and the Liberals. It seemed like the anyone-but-Conservative voters were well and truly divided.
The NDP knocked on more doors than ever before, it had more volunteers, it broke all its fundraising records. But it wasn't enough to hold back the Liberal tsunami.
Mr. Mulcair promised a balanced budget while Mr. Trudeau said he would run small deficits and the NDP Leader found himself being slowly outmanoeuvred on his left by a party that is traditionally more centrist. And while Mr. Mulcair was solid and statesmanlike during debates, the Liberal Leader came across as youthful and energetic – providing, for those voters who desperately wanted change, a much starker contrast to Mr. Harper.
Then there was the niqab. Mr. Mulcair's defence of an Ontario woman who wanted to wear the Islamic veil over her face during a citizenship ceremony drove significant numbers of NDP supporters in Quebec to look elsewhere for a place to park their vote. That marked the tipping point for those in other parts of the country. The Liberals rose in popular support while the NDP sank, never to resurface.
In the end, say the New Democrats, Mr. Mulcair will go down as a man whose party was defeated in 2015 on a matter of principle.
"That's his way of operating, that's his career," Mr. Bélanger said. "He has always defended minorities all his life and he was not going to join a bandwagon based on poll numbers."