Dewar's mandate, announced Friday during a caucus conference call, will include guiding the NDP in staffing and reorganization both at the party level and inside the parliamentary wing.
NDP insiders say the caucus responded positively to the decision due to Dewar's positive rapport in and outside the party.
Mulcair, who quietly celebrated his birthday this weekend with family, was also expected to break his silence this week after remaining out of the public eye since election night, when his party was pared down to just 44 MPs.
"You will see Mr. Mulcair in the coming days but his priority now is preparing caucus to hold the government accountable," said Mulcair's Director of Communications Shawn Dearn.
Since the election, Dewar and outgoing party members such as Halifax's Megan Leslie and Toronto's Peggy Nash, have been cleaning out their offices while about 300 staff members are out of work.
Longtime New Democrat Peter Stoffer, who lost his east coast riding of Sackville—Preston—Chezzetcook, says he feels for the "poor people" who worked for him that are now unemployed.
"I know there's not much we could have done," Stoffer said. "We ran probably the best campaign we ever did. We thought we had the numbers, it just didn't turn out to be right. It is what it is."
Stoffer will be in his unique Ottawa office this week, which features a pool table and dozens of hats and buttons he has collected over the years, to mark the end of 18 years on Parliament Hill.
"I'm going to sell that obviously," Stoffer said. "All the money goes to charity. Everything that I have — the hats, the pins, the buttons, the pool table, all of that stuff, I always said will be donated to charity when I leave politics."
As the parting process continues for several team members, Mulcair has been reaching out to his caucus and trying to reassure NDP faithful.
In an email distributed to donors on Friday, Mulcair acknowledged the election results "weren't exactly what we had hoped for."
The party's results remain painful for supporters who thought forming government could be possible for the first time under Mulcair's stewardship.
"They're (the NDP) back to exactly where they historically always were," said Carleton University political science professor Jonathan Malloy. "Obviously they lost more than half their seats, they're no longer in that contending position where they were for the last four years. That has to hurt."
Nathan Cullen, re-elected in the B.C. riding of Skeena — Bulkley Valley, says it is good to reflect on what happened but he says he isn't "interested in moping around."
"The measure of the party and the person is how you react to difficulty, not what you do with wild success," Cullen said. "You take your moment ... then you get on with it and get back to work."
Stoffer also said the party continues to support Mulcair.
"Mulcair put his heart and soul into this party and worked very, very hard," he said. "I'm sure he is very disappointed at what happened but if I was talking to him right now, I would say 'have your head high, you did your best.'"
Stoffer said he doesn't think Monday's outcome was a personal reflection on the NDP leader, but rather voters wanted to go in a different direction by supporting Trudeau.
"Because we love this country so much, we have to respect and honour that decision and we go forward," he said.
Mulcair has promised he is in it "for the long haul" but his political fate is tethered to a party leadership review that will be held during the NDP convention in Edmonton this April.
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