But the NDP leader says the lessons learned from his late predecessor, whose memory continues to generate wave after wave of goodwill, have made it easier for New Democrats to make the transition to the post-Layton era.
"He taught me a lot, and it's served me well in the past few months as I moved into the leadership role," Mulcair told The Canadian Press in an interview as he prepared to mark Wednesday's first anniversary of Layton's death.
Moreover, Mulcair said, Canada's fond memories of Layton have helped him break the ice as he's travelled the country introducing himself to Canadians.
"Whenever people come up to me and talk about politics or the party, there's always a smile on their face when they talk about Jack. So it's still a great opener."
Canadian Heritage Minister James Moore once called Mulcair the antithesis of Layton. While Layton was perceived as a "nice guy" with a sunny disposition, Moore labelled Mulcair "as vicious a politician that I have seen in 12 years."
"He goes for the throat and he is the anti-Jack Layton," Moore told Yahoo Canada last March when it was evident Mulcair was about to win the NDP leadership contest.
Partisan hyperbole aside, Mulcair acknowledged he and Layton "are very different people."
"I come out of a completely different political school from Jack."
Whereas Layton honed his political skills while serving on Toronto's city council, Mulcair cut his teeth in "the pretty rough-and-tumble neighbourhood called the Quebec National Assembly."
"It's a much coarser neighbourhood to practice politics in in Quebec City. You know, it's a very divisive atmosphere," said the one-time Quebec cabinet minister.
Layton, Mulcair added, was "extraordinary and unique" and it would be pointless to try to replicate him.
"I've said since the beginning, I'm not going to try to replace Jack. I'm going to try to succeed him by being my own person."
That said, Mulcair said his observations of Layton's leadership style have helped him temper his own more aggressive, impatient instincts.
For instance, when Mulcair first joined the NDP caucus in 2007, he was sometimes frustrated by the 'go-around' sessions — seemingly endless, repetitive meetings at which MPs debated issues and batted ideas back and forth.
"Sometimes I would find the go-arounds in caucus to be really long processes, but then I realized what (Layton) was doing. He was working with every single person in the room and there was a real art to it.
Mulcair said that approach "inspired me quite a bit" when it came to pulling the NDP team back together and naming a shadow cabinet following the sometimes-bruising, seven-month leadership race.
"As we made choices, we made sure everybody was included, we made sure that we were going to show the team was there and everybody was having a good place in it and everybody would feel that too, internally. And I think that's something I can honestly say was inspired by the type of work and attitude that I'd always seen from Jack."
Mulcair said he also learned by watching Layton interact with the thousands of people he met with on the road.
"Jack was about working with individuals. He didn't just talk about love and caring for other people. You had to see him in action. I mean, he would walk up to somebody who wanted to talk to him, there was real eye contact, there was real human contact," he said.
He also learned something about the fine art of political persuasion from Layton.
"Jack rarely tried to convince people by saying to them, 'This is what I'm going to do for you.' Jack had a way of talking to people, which was, 'Things have to change, here's how you can help bring about that change.' That's subtle but it's something that Jack really did intuitively and it's something I picked up on."
Mulcair said he's tried to adopt a similar approach, "rather than lining up policies and saying this what we're going to do, it's we want to listen to you, we want to work with you and we think we can do things better together."
Whatever the recipe, the transition from "Smiling Jack" Layton to the more combative Mulcair has gone more smoothly than Moore — and many pundits and even some New Democrats — initially predicted.
The NDP has not fallen apart since Layton was claimed by cancer a year ago Wednesday. Indeed, quite the contrary.
The party is running neck and neck with the ruling Conservatives in opinion polls. It's holding strong in its newfound base of Quebec, which delivered 58 of its 75 seats to the Layton-led party in the 2011 election, vaulting the NDP into official Opposition status for the first time in its 50-year history.
And it seems to have united almost seamlessly behind Mulcair.
"I think (Layton) would be pretty proud," he said.
"We went through a rough year as a group.... We've set down roots here in Quebec, we're looking strong in the rest of Canada, our numbers are strong and the team is doing well.
"I think that's one of things he'd be happiest about, because Jack was a leader who led from his caucus."
For his own part, Mulcair said he finds it "humbling" to be the new keeper of the house that Jack built.
"Millions of Canadians chose to follow us because they agreed with Jack and now the job for us is to make sure that we build on that and that's a humbling task," he said.
"I mean, you realize you've been given something that's been worked on hard and you've gotten this great result and we've got to really take care of it and build on it. That's the heritage."
Also on HuffPost