It's budget day. Deficits, debts and the state of the books will likely be the top of the talk. It's important stuff. Look at the last election. The New Democrats lost – or so the fable has it – because they made the mistake of campaigning on a balanced budget. Tom Mulcair pledged not to run a deficit. Down went the ship.

As a consequence, the party has started another round of soul-searching. The Canadian left has been doing this since the invention of the radio. Never-ending navel-gazing. Do we compromise our principles in the pursuit of power, or adhere to the socialist creed? Go moderate to expand the voter pool, or stand firm on ideals with scant hope of ever gaining power to implement them?

But as the working-class party begins its leadership campaign, is this really necessary? Do the New Democrats have their story straight on what happened in that 2015 campaign?

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Funny thing, says Karl Bélanger, who worked alongside both Jack Layton and Mr. Mulcair, but in that election the much pilloried Mr. Mulcair was only following the Layton economic script. Balanced budgets? Mr. Layton campaigned on no deficits in the 2008 election even though the economy was starting to sink. In the 2011 election he did so again and stuck the landing. The party won Official Opposition status.

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In 2015, Mr. Mulcair had good reason for staying with Mr. Layton's moderate line. The NDP led all polls. It was on the brink of winning. Why endorse deficits and raise the spectre of the big government bogeyman? Why spread fear among voters that he would tax and spend their brains out?

Of course things didn't turn out so well. The party lost 51 seats. Mr. Mulcair underperformed in the debates. But did the moderate platform, one which Mr. Bélanger says was still more left than Mr. Layton's, have much to do with it? Or was it an unavoidable brutal turn of events in Quebec?

The NDP story in these times is the tale of two out-of-the-blue electoral shockers in that province. In 2011, the Layton-led party began the campaign hoping to win maybe seven or eight seats in the province. Freakish thing No. 1 happened. Deus ex machina, Gilles Duceppe's Bloc Québécois utterly collapsed. Because of the hard work of the Layton/Mulcair team in the province, the New Democrats were there to pick up the pieces. They won an astonishing 59 Quebec seats.

At the outset of the 2015 campaign, they appeared to be on target to hold the great majority of them. Freakish thing No. 2 happened. The issue of women's headgear in the voting booth, the niqab controversy, came to dominate the proceedings. In keeping with his party's multicultural sensitivities, Mr. Mulcair took the principled stance of niqab tolerance. It turned Quebeckers away in droves. He lost 43 of the 59 seats.

The balanced budget promise had very little to do with it. Nor was it the big problem in the rest of the country. There, when voters saw the NDP tanking in Quebec, they turned to the Liberals as the Stephen Harper stopper. Even so, the NDP lost only eight seats in the rest of the country, finishing with 44 across the country, its second strongest showing in history.

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Discontent is understandable, but the party is running a risk of ruinous overreaction. Mr. Mulcair was precipitately sent to the gallows. Radicals demanded a hard left turn. Balanced budgeting has become bad talk.

They forget something. They forget that logic often doesn't determine political outcomes. Accidents and ill-fortune do, such as when the FBI director torpedoed Hillary Clinton by going public with news of an investigation, or when the RCMP did the same to the Liberals in the 2006 campaign or the niqab issue routing the NDP in 2015.

The New Democrats rose under Mr. Layton. They continued that rise, moving to the precipice of power under a leader staying his course. Why on account of a campaign's cruel twist of fate would they want to turn hard left and change that script now?