The sleepy NDP leadership race has heated up with the release of competing poll results and a surprise endorsement from the late Jack Layton's mother.

Ottawa MP Paul Dewar's campaign has released survey results which his officials say suggest that Thomas Mulcair, a Montreal MP and the party's deputy leader, is supported by 25.5 per cent of NDP members.

Support for Toronto MP Peggy Nash stood at 16.8 per cent, Dewar at 15.1, British Columbia MP Nathan Cullen at 12.8, former party president Brian Topp at 12.7, Manitoba MP Niki Ashton at 9.5 and Nova Scotia pharmacist Martin Singh at 4.1.

It suggests Dewar is the top second choice of party members, putting him in good position to make a come-from-behind win.

However, Topp's campaign says it has done its own live interviews with 7,500 party members, which show Topp with 28 per cent support.

While the Topp camp questioned the reliabiity of "Robo-call" polls, the Dewar camp responded that Topp's survey was not a scientific poll at all.

Layton's mother endorses Topp

Meanwhile, Topp has been given a boost from Doris Layton, who says he's "very much on Jack's wave length."

"Jack and Brian worked closely together through the years. They can almost finish each other's sentences," she says in a statement posted Monday on Topp's website.

"I feel secure with Brian's leadership that the NDP will definitely follow Jack's path -- a path that will lead the NDP to form government in 2015. And Jack's spirit will live on."

A portrait of the late NDP Leader Jack Layton sits in flowers at a makeshift memorial outside Toronto City Hall on Friday, Aug. 26, 2011. Layton died Aug. 22 after a second cancer diagnosis. Ryan Remiorz/Canadian Press

Layton died of cancer in August, just three short months after leading the NDP to a historic finish in the May 2 election, which vaulted the traditionally third- or fourth-place party into the role of official Opposition.

Topp, a key backroom strategist throughout Layton's tenure, was one of a handful of confidants who helped Layton craft a deathbed manifesto for social democracy. He has amassed endorsements from a number of party luminaries, including former leader Ed Broadbent and former Saskatchewan premiers Roy Romanow and Lorne Calvert.

Poll data released on heels of Quebec City debate

Topp and Mulcair were the only two of the seven contenders vying to succeed Layton who appeared to be effortlessly at ease in both official languages during Sunday's all-candidates debate in Quebec City, the first to be conducted almost entirely in French. Dewar was handicapped by his laboured French.

NDP federal leadership candidates debate in Quebec City on February 12 (Clement Allard/Canadian Press)

The Topp campaign speculated that Dewar released his poll results Monday to deflect attention from his poor performance in Sunday's debate.

The Dewar poll also shows Quebec MP Romeo Saganash, who dropped out of the race late last week, with 3.6 per cent support.

Dewar's campaign said the survey of 6,373 party members was conducted Feb. 8-9 by automated interactive voice response, and is considered accurate to within plus or minus 1.19 percentage points, 19 times in 20.

The poll also asked New Democrats to identify their second choices. Dewar came out on top on that score, his campaign officials said, with 21.2 per cent saying he's their second choice. Nash had 19.4 per cent support, Mulcair 16.7, Cullen 14.4, Topp 12.4, Ashton 10.7 and Saganash 3.6.

In an email to campaign staff, Topp campaign director Raymond Guardia, disputed the results of the Dewar poll.

"Needless to say, we know from our own polling and canvassing that the findings don't reflect what's happening on the ground," Guardia says in the email, released by the Topp camp.

"In the past two weeks, our campaign has conducted live telephone interviews (not 'robocalls') with 7,500 confirmed voting members and 28 per cent intend to vote for Brian Topp in the upcoming leadership race."

In a swipe at Dewar's laboured French, Guardia said Topp has momentum because New Democrats are looking for a leader who can "win in Quebec, can win in Canada and that can speak to Canadians fluently in both official languages."

The Topp camp did not release other findings from its polling.