Prime Minister Stephen Harper formally launched the campaign Sunday for the Oct. 19 election, after two months of polls showing Mulcair, a 60-year-old lawyer leading a party that's never formed government, in a small but steady lead.
The New Democrats favor corporate tax hikes, a C$15 ($11.40) minimum wage and subsidized national daycare, but have shifted away from their socialist roots by, for instance, abandoning calls to nationalize banks. Still, the prospect of a win by a leftist party with few members experienced in government threatens to spook investors, undermine an already weak Canadian dollar and provide a new test case of how an activist challenger fares against a pro-austerity incumbent.
"If they don't win with Tom, who is so astute politically and is not the very left-wing branch of the NDP, I doubt they'll win with anybody," said Monique Jerome-Forget, a former Quebec finance minister and cabinet colleague of Mulcair from his days as a provincial Liberal.
The NDP was formed in 1961 and while it periodically held the balance of power it never finished better than third in national elections until 2011. In that year, then-leader Jack Layton led a breakthrough largely based in Quebec, where Mulcair was his lieutenant. The NDP won the second-most seats and became the official opposition.
"I'm pre-Jack Layton. I remember the days that we could get together in a minivan," said Brian Masse, a New Democrat first elected in 2002. Suddenly, they had over 100 lawmakers, more than double their previous best. Then Layton died and Mulcair won a leadership race as a candidate of moderation.
Under its new leader, the party's polling numbers sagged, wallowing behind the Conservatives and the resurgent Liberals led by Justin Trudeau, the son of former Prime Minister Pierre Trudeau. A turnaround began in spring, propelled by a surprise NDP victory in Alberta, home of Canada's oil patch and Harper's base, which gave the federal party credibility as a viable governing alternative.
Mulcair also benefited from being ignored by the Conservatives during pre-election attack advertising against Trudeau, his rival for the substantial pool of voters seeking change. In recent days, Harper has tacitly acknowledged Mulcair's frontrunner status by turning his guns on the NDP as a party that "would wreck our economy" led by an opportunistic career politician.
The NDP and its predecessor party have won power in six provinces over the years, but its inexperience often led it astray. After a surprise victory in Ontario in 1990, the government of Bob Rae quickly split between its left-wing base and its pragmatists as a recession set in.
"We were doing too much," Rae wrote in his 2006 book, From Protest to Power. "Already in that first year there were dramatic conflicts between spenders and savers, between advocates and managers."
The government controversially dropped one of the party's key promises, public ownership of all car insurance, to focus on the economy. "Moving from a party of protest to a government in power was more difficult than we thought," Rae wrote. He lost the next election and the NDP reverted to Ontario's third party.
Mulcair, second eldest of 10 children, worked in the civil service before being elected as a Quebec Liberal. He served as environment minister, clashed with his premier over a development project and quit cabinet rather than accept demotion. In 2007, he ran for the federal NDP and took a longtime Liberal seat, a toehold that led to the 2011 breakthrough.
The NDP continued to soften its image -- removing references to "socialism" from its constitution though remaining a member of Socialist International, a worldwide association of leftist parties. It abandoned calls for withdrawing from NATO and toned down policies against free trade.
While Mulcair is a pragmatic centrist, left-wing stalwarts like retiring lawmaker Libby Davies say they accept a "sense of responsibility about where we're headed towards."
Stephen Lewis, a former Ontario NDP leader whose father led the national party, said ideologically fixed positions are passe but the party remains true to its roots. "The idea of a social democratic party coming to power for the first time in its history in the country federally is so overwhelming in the implications that it's likely to dampen down the natural tensions that would grow."
Mulcair has not yet said much about what the NDP would do to spur growth in Canada, where the oil shock and lagging exports have led to five months of economic contraction. Of the country's four major pipeline proposals, he backs just one, Energy East, which is under pressure in his native Quebec. One adviser acknowledges Mulcair cannot compete for prime minister while being against all pipelines, and so has recently criticized the approval process for Energy East rather than the line itself.
The party's 2013 policy book calls for taxing capital gains at the same rate as salaries, keeping a "low interest rate policy," limiting bank mergers, creating a "revenue generating carbon market" and making corporations "pay a fair share," while not saying how much it would increase corporate taxes.
On the campaign trail, Harper warns an NDP government would "adopt policies such as in Greece: unlimited spending, major deficits, higher taxes."
Adding to the uncertainty is voter unfamiliarity outside Quebec with Mulcair himself -- particularly in contrast to Harper, who has governed since 2006, and Trudeau, who grew up in the national eye. Mulcair, who earned accolades for his grilling of Harper in the legislature, has taken to speaking of his family's middle-class roots and hard-work ethic.
He's a private man, his MPs say, and previously served as Layton's enforcer, earning him the nickname "Angry Tom." Trudeau, who draws large crowds but trails Mulcair in polls on who would make the best prime minister, hopes to portray the NDP leader as having a similar temperament to Harper.
"Tom needed to sort of reassure people he was a flesh and blood guy. He did roofing in university. When I tell people that, it answers a lot of doubts," said Charlie Angus, a long- time NDP lawmaker.
The party used to think its purpose "was to be the conscience of the nation" rather than to win. Now "our base understands it's about forming government," Angus said.
"We've matured. I don't think it's that we've sold any of our values out. We've just stayed focused on what Canadians want from us, which is an alternative, progressive government."
