MONTREAL—If he wants to avoid spending the 2019 campaign walking on the shards of yet another broken signature promise, Justin Trudeau has little choice but to make good on his promise to legalize marijuana in time for the next election.

Of the many commitments the prime minister made on the way to his majority victory some were more emblematic than others. The Liberal embrace of deficit spending, the vow to change the voting system in time for 2019 and the legalization of marijuana fall into that category.

On the issue of not letting a deficit stand in his way of his policy ambitions one could argue that Trudeau has delivered in spades. Or alternatively that he broke his word the moment he presented the country with a deficit three times larger than previously advertised, with no solid timeline to return to budget balance.

Trudeau has turned his back on the search for an alternative to the first-past-the-post voting system. With electronic and compulsory voting also off the table, there is little left of the Liberal promise to make sweeping changes to the way Canadians elect their government.

That leaves the legalization of marijuana — a commitment that strategists believe went a long way to attract a cohort of first-time voters to a) cast a ballot and b) to support the Liberals in 2015.

If only to counter the perception that Trudeau can’t be counted on to keep his word, delivering on the marijuana promise before Canada next goes to the polls has become non-negotiable.

But it will not be a cakewalk.

The prime minister’s promise has always been more popular than his own party. That is still the case as the government readies to introduce its marijuana bill later this week. But polls suggest that as Canadians hear more details about the plan more of them may be having second thoughts. Support for the measure was always high, but it may also always have been soft.

A Nanos poll published last August pegged support for the policy at an overwhelming 70 per cent. That score was in line with election polls on the same issue. But a RPG Research Group survey done just as the government was signalling the imminent introduction of its marijuana bill last month found that the pro-legalization cohort had shrunk to 51 per cent.

It could be that the reality that Canada is going further than just removing the consumption of cannabis from the Criminal Code is sinking in. In the last campaign, there was plenty of anecdotal evidence that the distinction between decriminalizing and legalizing marijuana was not always uppermost in the minds of many voters.

Over the past few months the debate has shifted from pure politics and party branding to public health concerns. It could be that the arguments pertaining to the risks of making marijuana widely available on the legal market are having an impact.

And then there is the body language of the provincial governments. It is they that will have to do the heavy lifting and create an infrastructure to distribute and sell cannabis once the federal bill is passed. They are warily waiting to see the fine print of the legislation.

Take Quebec. It has long been ahead of the provincial curve on a host of sensitive progressive issues. Over the past decades the National Assembly pushed the envelope on abortion rights, same-sex marriage and more recently medically assisted death.

But that benevolent attitude will not necessarily extend to marijuana. Last month Quebec’s Health Minister Gaétan Barrette complained that the federal government was handing the provinces a public health hot potato. The Coalition Avenir Québec has serious reservations about the federal plan. On this, there will not be a unanimous motion of the national assembly. In the RPG poll, support for Trudeau’s marijuana plan in his home-province was at the very low end at 37 per cent.

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Among the larger provinces, Ontario has been the most enthusiastic about the federal intention. In light of the unpopularity of Kathleen Wynne’s Liberal government, that may be more a curse than a blessing.

If all goes according to the federal plan, the legislation that is to be tabled on Thursday in the House of Commons will pave the way to the legal selling of marijuana across the country by the summer of next year. What will happen between now and then is a real national conversation about Canada’s approach to cannabis.

Chantal Hébert is a national affairs writer. Her column appears Tuesday, Thursday and Saturday.

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