"The NDP will be a partner for the development of our energy resources when we form a government in 2015," Mulcair told a Calgary business community luncheon Tuesday.
"We will work with you so that the rules are clear and that the public has confidence in what we're trying to do together."
Listening to Mulcair's speech were representatives from oilsands giant Suncor Energy Inc. (TSX:SU) and pipeline giant Enbridge Inc. (TSX:ENB) — the company behind a controversial B.C. pipeline proposal Mulcair said he remains "adamantly" against.
Mulcair reiterated his disdain for how the Conservative government handled China's CNOOC Ltd.'s $15.1-billion takeover of Nexen Inc., which is expected to close this month, as well as Malaysian firm Petronas' $6-billion takeover of Progress Energy Resources.
Late last year, Ottawa determined both would be a net benefit to Canada under the Investment Canada Act, but said major deals by state-owned enterprises would have to clear higher hurdles in the future, particularly in the oilsands.
Mulcair said foreign investment can be a "major benefit" to Canada's economy, with overseas money helping develop its natural resources.
"But it requires a coherent and strategic vision that creates the right environment for foreign investment, while ensuring our own, while ensuring Canada's, interests," he said.
"Unfortunately, what we have seen from the federal government is not only a lack of vision or understanding of this reality, but sincerely, we've seen a lot of sheer incompetence."
Mulcair stressed that the NDP's position is "anything but" anti-foreign investment.
"Of the hundreds (of deals) that have taken place in recent years, we have opposed one. We have opposed CNOOC's takeover of Nexen and we opposed it because the public didn't have the information to come to a right decision in that case," he said, calling for more public involvement in those decisions.
When it comes to environmental regulations, Mulcair said he's sure there would be some energy players that would welcome a loosening of the rules. The smart ones, however, would realize that's a "poisoned chalice" and that companies need a "social licence" from the public to get their projects going, not just a regulatory nod.
Mulcair said he's in favour of pipeline projects that would deliver western Canadian crude to refineries in the eastern part of the country that currently rely on expensive foreign imports, provided there is a "rigorous" environmental review process in place.
But he remains "adamantly" opposed to Northern Gateway, a $6-billion Enbridge project to connect oilsands crude to the West Coast for export to Asia.
"It is madness to think of bringing those super tankers into that pristine coast. It is a non-starter," he said.
"It is the most abject misunderstanding of the importance of protecting the environment that I have ever seen in Canada."
Much of the problem, he said, has to do with Enbridge itself, having been labelled the "Keystone Kops" by the National Transportation Safety Board for its handling of a 2010 oil spill in Michigan.
Mulcair was less harsh on a proposal by TransCanada Corp. (TSX:TRP) to connect oilsands crude to U.S. Gulf Coast refineries, saying it's up to the Obama administration to decide on the Keystone XL pipeline.
"I would have made it a priority to take as much product as we could from the west to the east," he said.
Mulcair's efforts to sell the NDP's vision in a province known as a bastion for Conservative support were quickly dismissed by Calgary Conservative MP Michelle Rempel.
In a statement, she pointed to Mulcair's past comments against the oilsands, free trade agreements and pipeline projects.
"Thomas Mulcair’s agenda is an anti-Alberta agenda that would kill jobs and economic growth in Alberta and across Canada," said Rempel, parliamentary secretary to Environment Minister Peter Kent.
"Alberta can rest assured our Conservative government will continue to oppose his dangerous and irresponsible economic plan."
Ben Brunnen, chief economist at the Calgary Chamber of Commerce and director of policy and government affairs, said there was some common ground.
"From a high level, I think we can all agree on the objective, of the importance of natural resources and energy resources as part of the national Canadian agenda. Alignment with a national energy strategy is very important for all energy producers as well as access to new markets," he said.
"Where we'd like to see stronger support from all federal leaders is in relation to West Coast access. Getting our product to market off the West Coast will be critical to expanding our energy export markets."
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