In an interview with Quebec magazine L’actualité for its August edition the NDP leader is asked what his position is on Energy East. “On est contre ce pipeline,” the magazine quotes Mulcair responding, which translates to “we are against this pipeline.”

It’s the final step in a significant reversal of policy for Mulcair on a project the Globe and Mail described in 2014 as the “cornerstone of the NDP leader’s energy policy.”

Earlier this year, Ricochet conducted multiple interviews with NDP energy critic Guy Caron. In April he promised an NDP position on the pipeline would be forthcoming by June, but in a follow-up interview in July he argued that the role of government was to improve a broken environmental assessment process and refused to say whether an NDP government would approve the pipeline.

The lack of a clear position was unpopular among the NDP’s progressive base, who argued that if the pipeline were built it would be impossible to keep most of Alberta’s oil in the ground, something many scientists have stated is necessary to avoid catastrophic climate change.

Mulcair makes his clearest statement yet on the pipeline in the interview, on newsstands now in Quebec but not available online. We’ve translated the relevant passage from its original French below.

When asked “What is your position on the Energy East pipeline, which crosses Quebec on its way to New Brunswick?” Mulcair responded:

“We are against that pipeline. Harper has dismantled our environmental laws, so that we can no longer conduct serious evaluations of pipeline projects. We also need to assess the greenhouse gas emissions that will be produced upstream in Alberta. The NDP agrees with the idea of moving natural resources from the west to the east of the country, better that than sending them abroad in a raw state and losing thousands of good jobs. But it must be done correctly, and that is not the case right now. And furthermore, the idea of a port in Cacouna, in the middle of a beluga nursery, was utter madness!”

It’s a far cry from a July 5 interview in the Calgary Herald, in which the NDP leader was quoted as saying, “I know Energy East has not been studied. You cannot say ‘yes’ to Energy East right now, because we don’t have a thorough, credible environmental assessment process. We’ll bring that in. We’ll make sure the public is onside and answer all their questions. It can be done. But you have to be sure that you bring people along.”

It’s farther still from the NDP leader’s support for the pipeline through much of 2014. But that changing position may reflect a changing attitude amongst Canadians towards climate change.

Are parties catching up to public opinion on climate change?

In Quebec, a poll done in October 2014 found that two-thirds oppose Energy East. For the NDP, the threat of losing progressive Quebec voters over their failure to oppose the pipeline is very real. Last fall a crowdfunder to oppose the pipeline raised almost $400,000 in a week, almost all in small donations from Quebecers. In the rest of Canada opposition has been less overwhelming, but the same poll found half of Canadians oppose the pipeline.

It should be noted that the NDP leader allowed himself wiggle room in his statements to support a different pipeline from west to east, but it appears this particular project will be dead if the NDP form government.

Now, with New Democrats appearing to offer a clear position for the first time, attention will turn to the Liberals. They too have offered confusing and sometimes contradictory positions on the pipeline. With all other parties now clearly for or against the project, pressure will mount on Liberal leader Justin Trudeau to pick a side.

At last report, Canada’s Conservatives support Energy East, while the Greens, Bloc Québécois and now NDP oppose it. A few months ago, with the NDP and Liberals unwilling to commit to a position, it looked like Energy East might not get much attention during this fall’s election campaign.

Now, with the party leading in public opinion polls coming out against the pipeline, the project looks likely to become a defining issue of the campaign.