QUEBEC - New Democrats are invoking the spirit of Jack Layton as they prepare for the new parliamentary session without their late leader.

Layton's widow, Olivia Chow, opened a caucus retreat Wednesday with an emotional plea to fellow MPs to work hard and stay united as they pick up the torch.

But their unity was put to the test almost immediately as interim leader Nycole Turmel announced rules for MPs who enter the contest to choose Layton's permanent successor. The rules, which were not clearly understood by a number of MPs and potential candidates, could give an edge to deputy leaders Thomas Mulcair and Libby Davies, should they take the plunge.

Choking back tears, Chow thanked her colleagues for all their love and support during Layton's final battle with cancer last month.

"Jack considered all of you his friends, it's like a second family," she said, her voice breaking.

"We have a lot of work to do to carry on his torch. And I'm so glad there's over 100 of us to take on that work because we know that we are united and strong in the values of the New Democratic Party of Canada that Jack embodied throughout his life."

Chow presented Turmel with two eagle feathers that she said were "very sacred" to Layton.

An aide said one of the feathers fell from an eagle that circled Layton and Chow while they were kayaking in the Queen Charlotte Islands shortly after the 2006 election. Haida Gwaii elders told Layton it was a "feather of leadership" and blessed it. The other feather was given to Layton later by an aboriginal leader.

"He used these feathers to guide his decision-making," Chow told the caucus, adding that she hopes they'll now give Turmel "the wisdom and the strength" to lead the party until a permanent leader is chosen in March.

The caucus retreat is grappling with how the NDP can be an effective Opposition when Parliament resumes Monday without being divided or distracted by the leadership contest.

Turmel also invoked Layton's spirit as she urged the 102-member caucus to stick together and stay focused on the immediate task: holding the Harper government to account, particularly on its management of the volatile economy.

"I know when I look out at all of you, I'm looking out at Jack Layton's greatest legacy: a team," she said.

"A team we have here that is united, a team that knows what it believes, a team with the experience and the commitment Canada needs right now ... a team that can't wait to get back to Parliament and take on Stephen Harper."

But her subsequent leadership rules -- aimed at ensuring no candidate has an unfair advantage or is in a conflict of interest -- created confusion and left the potential for discord.

Turmel told caucus that all candidates will have to give up their shadow cabinet posts, as well as any leadership roles in the caucus and on Commons committees. However, her principal secretary, Brad Lavigne, later explained to reporters that the rule does not apply to the prestigious title of deputy leader, held by Davies, who is considering a leadership bid, and Mulcair, a frontrunner who is almost certain to take the plunge.

Lavigne said the title is strictly honorific and does not carry any specific responsibilities. Still, he acknowledged deputy leader is "a very important position," one that enhances the stature of those who carry the title.

In the past, Davies and Mulcair frequently took the lead role in the Commons when Layton was absent. Lavigne said Turmel will choose her stand-ins as the need arises, on a case-by-case basis.

Turmel also left it up to prospective candidates to decide when to enter the race. That means Mulcair, who is also the NDP House leader, could continue for some time to play a key role in determining which MPs get to speak during the daily question period. Mulcair has said he's in no rush to announce his candidacy.

Potential contenders Peggy Nash and Nathan Cullen said they were under the impression that Mulcair and Davies would have to give up the deputy leader designation if they run for leader.

So was Quebec MP Francoise Boivin, who supports party president Brian Topp's bid. Topp has already recused himself from party decisions on the leadership contest and has promised to step aside as president as soon as he formally registers as a candidate.

"I don't think it would be fair (to keep the deputy leader title) so I agree with the decision of Madame Turmel," Boivin said initially.

When reporters pointed out that Turmel was not insisting that deputy leaders give up their titles, Boivin said there'd be more discussion later Wednesday "so we will see if we correct that."

While he was initially surprised to learn that Mulcair, a potential frontrunner, could keep the title, Cullen quickly got on side.

"As a potential candidate, I don't feel encumbered by somebody else having an honorific title," Cullen said, adding that party members will make their choice based on more serious considerations.

As for Mulcair remaining in the influential role of House leader until he declares his candidacy, Cullen said: "I guess this is the one advantage of actually liking each other. That distinguishes us from some of the other parties. I like Tom, I trust Tom."

Turmel told reporters the contrast between the NDP and the ruling Conservatives will be apparent during the fall sitting as her party focuses on the troubled economy. She said New Democrats will push the government to relax its plan to slash spending and eliminate the deficit, in order to invest in job-creating initiatives such as strategic infrastructure.

Finance critic Nash said the NDP wants the government, which accelerated its deficit-elimination plan by a year, to go back to its original goal of 2015.

"We of course want to see the deficit eliminated but what we're saying is you're going to make (the economy) worse if you act too quickly," Nash said.

"You can slow that down slightly and use the opportunity to invest in our economy, put people back to work ... and take advantage of rock-bottom interest rates."