NDP leadership hopefuls must give up their shadow cabinet posts while running for the party's top job, Interim Leader Nycole Turmel said Wednesday, even though two perceived front-runners may be able to keep their deputy leader titles.

Turmel also informed the party that candidates will have to give up any leadership roles in the caucus and on Commons committees for the duration of their leadership bids.

While Turmel's announcement, made during a caucus retreat in Quebec City, is intended to make the still-developing leadership contest fair to everyone, the rule has potential to create discord among the 102-member caucus.

Picking a leader is a new issue for the party, which was led by Jack Layton for nearly a decade before his death last month.

So far, the only person who has officially declared an intention to run for the NDP leadership is Brian Topp, the party president.

Topp announced his candidacy on Monday. He said he will resign his position as soon as he files his papers to run for the leadership.

High–profile MPs Thomas Mulcair and Libby Davies would be able to hang onto their shared title of deputy leader in the event they declare their intentions to vie for the party's top job.

The distinction arose after NDP spokesman Brad Lavigne told reporters that the rule doesn't apply to the role of deputy leader, as it is ceremonial and doesn't carry any real responsibilities.

Mulcair is currently serving as NDP house leader as well, giving him the authority to pick which MPs get to speak in Parliament. And until he formally announces his intention to seek the party leadership, he'll be able to stay in that role.

Mulcair has said that he is not rushing to make any announcements about a potential leadership bid.

So far, the party has decided that each leadership candidate will have to pay a registration fee of $15,000 and adhere to a spending limit of $500,000, during a campaign that will culminate in a leadership vote next March.

Support for a level playing field

Several potential New Democrat leadership candidates have already said they want to see rules in place that will make the lengthy leadership contest fair to all participants.

Nathan Cullen, the MP for the British Columbia riding of Skeena-Bulkley Valley, said he believes that leadership contenders should volunteer to drop their shadow cabinet positions.

"Nycole should make the suggestion, but I think it should come from all the candidates too. We should just do this thing," Cullen told The Canadian Press in advance of Turmel's announcement on Wednesday.

Cullen said that allowing contenders to keep high-profile roles would create an uneven playing field for other candidates.

Halifax MP Megan Leslie said she simply wants to see a set of rules in place that will make the contest fair to all participants.

"For me, the big question is what's fair and how do we make sure the playing field is as level as possible. Both within the group of people who are MPs who are running and people who aren't MPs who are running … whatever we do has to be fair," Leslie told CP.

Strategy talks underway in Quebec City

In Quebec City, the New Democrats are also discussing strategy for the upcoming parliamentary session after the death of their long-time leader.

Trinity-Spadina MP Olivia Chow, the late leader's wife, told attending New Democrats that she and her husband appreciated their support during Layton's final days.

"Of course, you know it means the world to Jack," Chow said Wednesday, at the start of the caucus retreat in Quebec City.

"Jack considered all of you his friends, it's like a second family. And 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 has said she will not make a run at the New Democrat leadership job.

Power Play host Don Martin said the person who eventually takes over the permanent leadership role will have the advantage of time as he or she settles into the job.

"Majority breathing room is the best thing the New Democrats have on their side and the Liberals, too, frankly," Martin said.

"Stephen Harper can do what he wants and has four years to do it. And the other parties have four years to prepare a battle plan to take him on in 2015."

With files from The Canadian Press