The selection of Thomas Mulcair as Leader of the NDP, and thus Opposition Leader, was not unexpected – yet in a number of ways proved to be quite original. Rather than selecting a charter member of the NDP family, the party reached out to a recent convert. And of course, for the first time, it chose a Quebecer. These two choices are not unrelated, we need remind ourselves, since there is no such animal as an experienced, publicly known Quebec politician who has limited his or her involvement to the NDP. The closest to fit the description is Mulcair’s main opponent, Brian Topp, who like Mulcair grew up bilingual in Montreal. But Topp’s NDP involvement was behind the scenes and largely outside Quebec.

Another unusual aspect of Mulcair’s leadership campaign was his largely ignoring the media, refusing the usual round of CBC interviews in favour of meeting party members directly. When he was finally interviewed on national television after being chosen in Toronto on the fourth ballot, many were surprised, as well as impressed, by his ease and articulateness in both languages. Indeed, he was much better in the interviews than in his short victory speech at the convention. Also original was the fact that he did a French-language interview on RDI before going to the CBC.

Mulcair’s ability to convince lifelong social democrats that he was their man, without pretending to be one of them, as well as the positive reception that greeted his victory in Quebec where the NDP has most of its seats, confirms the fact that he is the NDP politician best poised to keep the party in second place and thus the official opposition after the next election. A clear majority of Quebecers – unlike Canadians outside Quebec – see the values of the Conservatives as different from those of their society. Had another NDP leader been chosen, more Quebecers would have seen the Bloc Québécois as the party best able to articulate this difference, and the Bloc would have had a better chance of regaining seats from the NDP.

But what about defeating the Conservatives? During the leadership campaign, only Nathan Cullen was prepared to state explicitly that to do so would require a strategic alliance with the Liberals. Cullen’s unexpectedly strong showing reflects an understanding on the part of many more NDPers than might have been expected that this is indeed the case.

Rather strangely, in his post-campaign interview Mulcair dismissed such an alliance as impossible under Elections Canada rules, putting an end – temporarily – to speculation along these lines. Clearly he is not now prepared to invest political capital in such a difficult process. For the time being, Mulcair’s chosen path to power is the one articulated by all NDP leaders: forming an NDP government.

Except that unlike previous NDP leaders, he will be expected to actually deliver. As Leader of Her Majesty’s Loyal Opposition in Ottawa, Mulcair’s job is to present a credible, viable alternative to the team on the opposing front benches. However much they claimed to be prepared to govern, no previous NDP leaders faced this challenge. The revered Jack Layton was Opposition Leader only long enough to reap the glory of the late electoral breakthrough in 2011. Neither he nor interim leader Nycole Turmel had to measure up as a credible alternative prime minister.

In contrast to the leader of the centrist Liberals, a leader of the NDP needs to maintain a delicate balancing act between this posture of a credible alternative prime minister and fidelity to the party’s program and principles. During the leadership campaign, Mulcair could square the circle by evoking Layton’s legacy, since Layton had effectively blurred the distinction in his successful 2011 election campaign. But had he lived, Layton too would have faced the same challenge.

Simply moving to occupy the centre ground, as the NDP in Manitoba, for example, has been able to do, is not an avenue open to the federal NDP. There are simply too many divergent groups within the party and its wider constituency. Mulcair is a skilled strategist, but the Conservatives are also skilled and, with far more resources at their disposal, will do everything possible to bring these contradictions to the surface.

Nothing in the experience of the federal NDP has prepared it for this challenge. As time goes by, and Mulcair attempts to meet the frontal attacks of the Harperites, with the Liberals biting at his heels, disgruntled social democrats can be expected to grumble increasingly loudly that it is the mantle of Tony Blair, not Jack Layton, that Mulcair has donned. But Tony Blair, as Mulcair well knows, was able to win elections.

And then there will be the Quebec dimension. In his unexpectedly successful Quebec campaign, Layton succeeded in blurring another divergence: that between ROC and Quebec progressives as to the level of government that should be primarily responsible for the welfare of the people. Asymetrical federalism may sound good in theory. It can even seem workable when the government in Ottawa favours a small state. The difficulties arise when it gets down to the nitty-gritty of the platform of a progressive federal government in waiting.

There is an alternative approach, as proposed by Cullen. In the context of a strategic alliance with the Liberals to defeat the Conservatives, the NDP could accept certain Blairite policies as part of a common election platform without embracing them. They could even use such a deal to avoid rejecting their “Sherbrooke declaration” that an NDP government would recognize a sovereign Quebec after a 50-per-cent-plus-one Yes vote in a referendum, while still reducing their vulnerability in English Canada.

Under our winner-take-all electoral system, such a deal is conceivable – though very difficult to attain, given the incentives that party organizations face. Still, it has dawned on many Canadians who do not share the Conservative worldview that our system turns third parties into spoilers, which, in today’s context, means spoiling the chances of defeating the Conservatives.

If this reality finds its way into the Liberal leadership campaign, there is a chance that the next election could herald real political change. A Lib-Lab strategic alliance should not result in a merger. The last thing we need is less choice on the centre-left, as happened on the centre-right. The real change would be toward an electoral system which gives voters a real choice among parties that, as a matter of course, govern in coalition.

For now, Mulcair is making the right moves, with encouraging poll numbers well beyond Quebec. His credibility as an alternative government leader reflects his effectiveness before the media. But the next election is a long way off. As it gets closer, he will have to defend, and indeed sell, his party’s program. Without adopting the program of a “New NDP” along the lines of Blair’s New Labour – or forming a strategic alliance with the Liberals – Tom Mulcair should not expect to move from Stornoway to Sussex Drive any time soon.