When Thomas Mulcair made his final pitch to New Democrats on Friday, he portrayed himself as the candidate who can stop Prime Minister Stephen Harper — now he will have a chance to prove himself as the new Official Opposition leader.

Mulcair said he ran a positive, upbeat campaign, that his only enemy is the prime minister and that he wants to rally "progressives of all stripes" behind the NDP.

Mulcair's roots in the NDP aren't as deep as the other candidates — second-place finisher Brian Topp said during the campaign he thought the former Liberal should be in the party a little longer before he tried to lead it.

Mulcair joined the party at the request of the man he succeeds, the late Jack Layton, when he agreed to run in a byelection in Montreal's Outremont riding in 2007. He won the Liberal stronghold and headed for Parliament Hill as the NDP's only MP from Quebec at the time.

Mulcair, 57, spoke often during his leadership campaign about how he worked "shoulder to shoulder" with Layton to grow the party in Quebec and how the hard work paid off last May when the party won 58 more seats.

High profile in Quebec

He has a high profile in Quebec, but Mulcair had to work hard during the campaign to broaden his appeal across Canada.

Mulcair has been called aggressive and impatient, but in an interview last year with CBC.ca he shrugged off questions about the impression some might have of him.

"My best answer to any of those questions is the fact that I have more MPs — the people who actually work with me —supporting my candidacy than all other eight candidates combined," he said during the interview in his Parliament Hill office when there were still eight people in the race. Romeo Saganash later withdrew because of lack of support, and he endorsed Mulcair, as did Robert Chisholm, the other candidate who started out in the race but didn't finish.

Mulcair collected more than 45 endorsements from caucus colleagues before the convention, and as the day progressed on Saturday he gained the support of several more after the third ballot when the choice came down to him or Topp.

He also had a long list of endorsements from provincial politicians and labour leaders.

One of Topp's biggest backers, former leader Ed Broadbent, stirred controversy during the final weeks of the campaign when he said he was worried about the direction Mulcair would take the NDP and questioned his commitment to social democratic values.

There was a lot of talk during the race of Mulcair wanting to move the party to the centre, but Mulcair responded by saying he wants to move the centre to the NDP.

Mulcair had strong support from Quebec, where he and nine siblings were raised by a French-Canadian mother and an Irish father in Laval, north of Montreal. As a result of his parents, he grew up in a bilingual home and speaking French,  an important factor in this leadership race.

Law career

He began his professional life as a lawyer and there are a number of jobs on his resume that Mulcair says have given him experience in public policy, management and leadership.

The political chapter of his career began in 1994 when he was elected to the Quebec national assembly. When the Liberals won government in 2003, Premier Jean Charest named Mulcair environment minister.

Mulcair quit Charest's cabinet in 2006 after refusing to sign over provincial park land to developers. He didn't run in the next provincial election and instead accepted Layton's invitation to join the federal NDP. There is no provincial NDP wing in Quebec.

When he arrived in Ottawa as Outremont's MP in 2007 Layton named him his Quebec lieutenant and he was also deputy leader before the leadership race was triggered by Layton’s death in August.

Mulcair said in the interview during his campaign that experience, elected and otherwise, is the best quality that he brought to the leadership, adding he has the kind of thick skin needed in politics.

"Quebec City is a tough neighbourhood to learn your politics in," he said. "It's very rough and tumble politics, so that's prepared me well for the work that I've done after."

The NDP set its sights on Quebec and the strategy used there, which clearly paid off, needs to be broadened in order for the party to claim victory in the next election, Mulcair said.

Cultural outreach

Moving from the opposition to government benches will involve reaching out more to cultural communities, First Nations and young voters, Mulcair said, and it will mean convincing Canadians that the NDP can manage the economy. Helpful in that effort would be securing some high-profile recruits from the financial and other sectors, he said.

If elected prime minister, Mulcair said, one of his first policy moves would be a plan to reduce greenhouse gas emissions that would include a cap-and-trade system. Mulcair said he is known as an environmentalist in Quebec and that the legislation he introduced there as a minister was the most forward-looking in North America at the time and probably still is to this day.

Mulcair said he would also resurrect a long gun registry, one that corrects the flaws he says exist in the current system that is being dismantled by the Conservatives.

"For the purposes of public protection you would need a form of registration of firearms, yes," he said.

Mulcair, whose son is a police officer, said he would make registration violations hybrid offences so that police could choose between charging someone with an indictable or a less serious summary offence depending on the circumstances.

What he loves about politics, he said, is turning ideas into concrete action and he's running for leader because he wants to take the NDP's ideas "and to make them real."