With just two weeks lefts before the party elects the new leader of the Official Opposition, and voting already underway, the attacks on Mulcair came fast and furious.
"How can you inspire people to vote for our party when you don't seem to be inspired by our party, how do you do that?" asked Ottawa MP Paul Dewar.
Toronto MP Peggy Nash, one of the leading contenders, asked Mulcair to provide details on his plan for party renewal and explain "what specifically did we run on in 2011 that you would change?"
Another top-rival, Brian Topp, suggested Mulcair was attempting to move the party "backwards into a divisive and distracting debate about ourselves."
Churchill, Man., MP Niki Ashton continued the barrage, asking Mulcair if he planned to change the party's language or direction and questioning why it didn't make more sense to just attack Prime Minister Stephen Harper.
A confident and beaming Mulcair said his rivals' attacks show that he has the support of the party's rank and file.
"We've been taking it as a fairly positive sign, when we get that many questions, that people are coming after us because they figure that our campaign is doing well," he said following the televised debate.
Answering questions about his new vision, Mulcair said the party should recognize some of its failures in the past.
"I think at the same time we have to be cognizant of the fact that between the Ontario border and the B.C. border we now hold a grand total of three seats," he said.
"So if we don't do something differently the next time around, it's guaranteed we'll get the same result."
Mulcair said the NDP has fought four federal elections in Saskatchewan, the province where it has its deepest roots, and hasn't won a single seat.
"We don't have any more trees"
To change its fortunes, the party must consolidate in Quebec, talk to Canadians and unite progressives of all stripes, Mulcair said.
A former cabinet member for the Quebec Liberals, Mulcair is one of seven candidates running for the party's top job, following the death of Jack Layton from cancer last summer.
Topping off the field are B.C. MP Nathan Cullen, who appeared reluctant to join the others in attacking Mulcair, and Martin Singh, a pharmacist from Musquodoboit Harbour, N.S., who has been accused of being Mulcair's "attack dog" during recent debates.
"Make no mistake — I am in this campaign to win, and my debate strategies are my own," Singh said.
The party will announced its new leader during a convention in Toronto March 23 and March 24.
So far, Mulcair leads the fundraising efforts, bringing in $226,000, followed by Topp with $193,000, Nash with $157,000 and Dewar with $152,000.
Cullen has raised $142,000, followed by Singh in sixth place with $57,000, and Ashton in last place with $37,000.
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