Linda McQuaig, a well-known author and journalist, was quoted as saying during a CBC television panel discussion on Friday that "a lot of the oilsands oil may have to stay in the ground" if Canada is to meet its climate change targets.
A Calgary Conservative incumbent, who was also on the program with McQuaig, accused the NDP of proposing a moratorium on the oilsands. Michelle Rempel also said it would kill jobs at a time of instability in the oil sector.
Alberta's Opposition Leader Brian Jean, whose Fort McMurray riding is in the heart of the oilsands, said on Saturday that McQuaig's comments were "deeply concerning" and he called on the province's New Democrat Premier Rachel Notley to stand up to the federal NDP.
McQuaig later posted on Twitter that the NDP position is that sustainable development means stronger reviews, which she says the government of Stephen Harper has undermined.
"NDP policy is sustainable development, overseen by strong enviro review process which Harper has destroyed," McQuaig tweeted on Friday afternoon.
The federal NDP campaign office noted that McQuaig clarified her remarks on Twitter, and it directed questions about them to her posts.
Cheryl Oates, a spokeswoman for Notley, said the provincial NDP's position on the oilsands remains the same.
"We've always been committed to the sustainability of the energy industry, which provides good, mortgage-paying jobs, and nothing has changed," Oates said.
The New Democrats could do little to blunt other politicians from chiming in.
Kyle Harrietha, the federal Liberal candidate for the riding of Fort McMurray-Cold Lake, accused Mulcair of holding two separate positions on the oilsands depending on his audience.
Rempel, meanwhile, accused Mulcair of planning to shut down Alberta and Canada's resource sector and said the comments couldn't be merely put off as those of a candidate who had gone off message.
"This isn't just some candidate," Rempel said of McQuaig. "This is a candidate that Mulcair is out on the record calling brilliant and articulate and saying that she'd be on the front bench with him."
Mulcair has in the past enthusiastically called a west-to-east oil pipeline for pumping Alberta's oilsands crude to tidewater a "win-win" which will mean better prices for the producers, and therefore more royalties for the producing provinces.
He said it must include a rigorous, transparent environmental review process and legislation to force oil companies to pay for the pollution they create, including any increase in greenhouse gas emissions.
Jean, however, accused the NDP of having a long tradition of campaigning against Alberta and its energy sector.
"Premier Notley may be a member and supporter of Thomas Mulcair's NDP but as Premier of Alberta she must actively repudiate this crazy idea in the strongest terms possible," he said.
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