Brian Topp, who was first to enter the NDP leadership contest and hopes to be the last one standing March 24, wants his party to stay firmly planted on the left.

Moving it to the centre, as he says rival Thomas Mulcair wants to do, would be a mistake, according to the veteran NDP campaign strategist and former party president.

"I don't think that we will succeed if we do that," Topp said in an interview this week. If there are two parties pitching liberal ideas in the next election, voters will choose "the real one," meaning the Liberal party, he said.

Topp was elected NDP president last June and stepped down when he threw his hat in the ring for leader following Jack Layton’s death.

As the NDP's national campaign director and election war room manager in four different elections, Topp worked closely with Layton. He said he favours moving the party forward based on the late leader's hopeful and optimistic approach to politics and "on a basis of the principles and values of our party."

In one of his policy documents, Topp said the party shouldn't lose touch with its "fundamental identity as a social democratic/democratic socialist party" and that the NDP might want to redraft its constitution to more fully capture its values and principles.

Topp said he would build on Layton's leadership style by offering positive proposals to voters instead of simply attacking the Conservatives.

"That's a winning political strategy for the NDP and one that I intend to continue," he said.

Rich should pay more tax

Among the proposals he's made so far in the seven-month leadership campaign is creating an income tax bracket of 35 per cent for earners over $250,000. Topp estimates that measure alone would generate an extra $3 billion, and raising corporate tax rates would bring in billions more.

The rich and profitable don’t need any more of the government's help and it's time for tax fairness, Topp has said throughout his campaign.

"I don't think there's any question that New Democrats strongly support these proposals and I've seen that all across the country," said Topp. "And we did some research to reassure ourselves that that's true."

He said there would be three main themes of a Brian Topp government if he were to win the leadership and next election: undoing the damage done by Prime Minister Stephen Harper's government to the public finances; acting on climate change; and closing the inequality gap in Canada.

Brian Topp launched his NDP leadership bid in September with the heavyweight endorsement of former leader Ed Broadbent. (Fred Chartrand/Canadian Press)

Topp advocates for a cap-and-trade system on carbon emissions, for a national transit strategy, for tax hikes, and for creating more jobs by pushing for more value-added development in Canada's industries, starting with the energy sector.

"Rather than building pipelines to export raw resources to China and Texas, we would do better to spend the same money building value-added industries here in Canada, to add value to our own energy resources here," he said.

The 51-year-old Quebec native, who lives in Toronto working for ACTRA, a union for film performers, has put out a series of policy papers and promises more but gave no clues on the subjects.

With four weeks left in the race, some divisions are finally starting to emerge between Topp and the other six candidates and he’s not holding back on pointing them out.

He has said Mulcair should be in the NDP longer before trying to lead it, and says they disagree on environmental and economic policies. Mulcair was a Liberal MLA in Quebec before winning a federal seat for the NDP in 2007.

'Beautiful breakthough' in Quebec can't be wasted

Topp is also making it clear the next leader should be fluent in both official languages. Paul Dewar, an Ottawa MP, is not.

Quebec was the key to the NDP's success in the May 2 election, electing 59 MPs for the party and pushing them to Official Opposition status for the first time in history.

"The beautiful breakthrough" in Quebec that Topp worked on for years with Layton and the NDP team "is a precious gift that we must not throw away," he said.

"And it's hard to imagine how we're going to hold it if our leader cannot speak to French-speaking voters in Quebec," said Topp, who was raised in a bilingual household near Montreal.

If he wins, he will ask one of the NDP's Quebec MPs to step aside so he can run in a byelection in his home province.

Topp, who worked on Parliament Hill for three years in the early 1990s before heading to Saskatchewan to be then-premier Roy Romanow's deputy chief of staff, said he originally thought he'd be running for a seat in 2015 when his two teenaged sons would be older, to become a member of a Jack Layton government.

Instead, he is now trying to fill the void left by his death.

While his opponents highlight the fact he has no elected experience, Topp said his biggest weakness is his modesty. When asked about his strengths, Topp said he's a bilingual Quebecer who has lived all over Canada and learned many lessons from Layton and Romanow's "economically literate and socially progressive government."

"I think that's a pretty good combination and one that I hope that members will consider," he said.