While admitting he is partly to blame for the NDP's third-place finish, Mulcair insists he should be leading the party into the next election, and will take that message to party members ahead of April's leadership review.
"There were shortcomings in that campaign, and of course I take full responsibility for it," the Montreal-area MP said in an interview with Chris Hall on CBC Radio's The House.
"[The niqab] hurt us terribly. It was measured. I can share with you that the polling we did showed we dropped over 20 points in 48 hours here in Quebec because of the strong stand I took on the niqab," Mulcair said.
The party was riding high in the polls when former prime minister Stephen Harper called an election last August. Mulcair said a short-sighted desire to hold on to that lead made the party risk-averse.
"We were extremely cautious. We had never been at that level before heading into a campaign and didn't know, perhaps, what to do to manage that lead," Mulcair said. "There was a sense in the campaign team, which was 'OK let's hold on to what we've got.'"
Mulcair has cleaned house since the election. The party's former executive director, Anne McGrath, left Ottawa to work with Premier Rachel Notley in Alberta. His chief of staff, Alain Gaul and his director of communications, Shawn Dearn, among others, were also let go in the wake of the Oct. 19 thumping.
The choice of which leaders' debates didn't help either.
Mulcair said he was too cautious on the federal election debates. (Photo: CP)
When the NDP backed away from its commitment to take part in the English-language broadcast consortium debate — to be broadcast on CBC TV, CTV and Global — it angered some party members who thought Mulcair was passing up an opportunity to reach a large audience.
"A good example [of being too cautious] would be the debates. Which ones did we choose to participate in, which ones we didn't choose to participate in. I was getting advice on that, but ultimately those were my choices. If you look back on it now, it's easy to see that those were not necessarily the best choices," he said.
In the 2011 election campaign, the English-language debate reached over 10 million Canadians. In 2015, the debates, organized by Maclean's magazine, the Globe and Mail and the Munk Debates, were watched by much smaller audiences with none of them reaching more than 2 million people.
Promises 'overshadowed' by balanced budget pledge
The party's big ticket promises, namely $15 a day daycare and a national pharmacare program, were overshadowed by its commitment to balance the books, Mulcair said.
Long-time party activists have argued that his steadfast commitment to balancing the books, despite worsening economic conditions, hurt the party among its social democratic base and those voters looking for dramatic change.
"When we talk about a social democratic vision — where we're going to remove income inequality in our society and do better on basic issues around poverty — then we have to say where the money is coming from, and we had that, but ... it was lost because of the debate over balanced budgets," Mulcair said.
"[The niqab] hurt us terribly."
The NDP's support for a women's right to wear a niqab contributed significantly to the party's crashing fortunes in Quebec, where a large number of voters backed the Conservative party's pledge to ban the headgear at citizenship ceremonies.
Mulcair said he stands by his defence of the niqab during the campaign, but says he did a poor job of selling his nuanced stance in his home province.
"There was a heavy price to pay. A lot of Quebecers put it on the level of women's rights and they saw the niqab as a symbol of oppression of women. And what we didn't communicate was, 'OK that's an understandable position, but once the courts have ruled in defence of people's rights, you have to respect that.'
"And I think that perhaps that was something that we had to have done a bit better. But it was so emotional. That's something that I have to change — my answers tend to be lawyer-like and a little bit too rational in the face of a very emotional debate," Mulcair said.
The NDP does not have a strong tradition of dumping its leaders after a losing election campaign, and Mulcair hopes that precedent applies to him. (Photo: Getty Images)
Despite the visceral reaction many Quebecers had to his stance on the niqab, Mulcair said the party still has a good base level of support in the province.
"We have 16 seats in the province of Quebec. Way down from the Orange Wave, it's a small consolation from where we were, but we do now have grass roots that's real in Quebec and we can take that and rebuild."
'What's your number?'
The NDP does not have a strong tradition of dumping its leaders after a losing election campaign, and Mulcair hopes that precedent applies to him.
All NDP leaders are subject to a leadership review every two years and Mulcair will face his at the party's upcoming convention in Edmonton in April.
He says there hasn't been a lot of blow back against him personally since the election, and party members have been broadly supportive of him staying on. But he won't divulge what percentage of support he would like from members.
"There were shortcomings in that campaign, and of course I take full responsibility for it."
"I'm not going to give a number, obviously, I'm going to wait and see how the convention rolls out but I have a sense inside of me of what would be required to have the confidence of the membership and the caucus. I'm going to keep working hard to get the best number possible in Edmonton."
Mulcair did conceded, however, that getting to at least 70 per cent support is a number that is being thrown about by party members as a base level.
"That's something we hear across the country, that sort of analysis," he said.
NDP party president Rebecca Blaikie has pointed to former prime minister Joe Clark's leadership review in 1983. Clark received 66.9 per cent of support from Progressive Conservative delegates at the party's convention that year, but considered it insufficient.
He subsequently called a leadership race and lost the contest to Brian Mulroney.
Also on HuffPost