The notion of a west-east pipeline is the cornerstone of the NDP leader's energy policy.
While he maintains Keystone is environmentally unsustainable and should never have gotten off the drawing board, Mulcair contends a cross-Canada pipeline would keep construction and refining jobs in Canada rather than exporting them to the United States.
But a report by the respected Pembina Institute doesn't concur with Mulcair's assessment.
The report estimates TransCanada's proposed $12-billion Energy East pipeline would actually result in a greater increase in greenhouse-gas emissions than Keystone.
And it casts doubt on its job-creating potential, arguing that the three Canadian refineries to which TransCanada proposes to pipe western crude aren't currently equipped to refine extra heavy oil from Alberta's oilsands.
The pipeline would also transport lighter crude but, even then, the Pembina report says the capacity of the proposed pipeline is greater "by a significant margin" than the capacity of the three refineries to deal with it.
Nevertheless, Mulcair is standing by his policy.
"When we talk about sustainable development of our resources in Canada, we talk first and foremost about adding the value here, including the jobs," he said Thursday.
"Keystone XL represents the export of 40,000 Canadian jobs. So as a matter of principle, we're saying, since that bitumen is moving anyway, move it in Canada, create 40,000 jobs here, get a better price for the producers, more royalties for the producing provinces, oh, and by the way, take care of Canada's energy security."
Mulcair said the cross-Canada pipeline should still be subject to a "complete, thorough, credible" environmental assessment. While he promised to review the Pembina report's numbers, the NDP leader said he'd be "very surprised" if it produced more greenhouse-gas emissions than Keystone.
"As a matter of principle between something like Keystone XL, which as far as we're concerned is a big mistake, and west-east, west-east is a better alternative," he said.
At a minimum, Mulcair said, building the pipeline in Canada would create jobs here instead of south of the border. And domestic refining capacity could be expanded over the longer term, he added.
"As a matter of principle with regard to natural resources, we've got to move away from the traditional Canadian tendency to simply rip and ship and not add value here. Value-added jobs are the way to go."
Natural Resources Minister Joe Oliver has denounced Mulcair's views on pipelines as "policy chaos and lack of vision."
But he had his own issues with the Pembina report.
"This report is flawed because it assumes that if the pipeline is not built, oilsands production will not occur," he said in an email statement from his office.
Like Mulcair, Oliver lauded the "high potential" for a cross-Canada pipeline to create "construction and operating jobs in Ontario, Quebec and Atlantic Canada."
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