NDP Leader Tom Mulcair says that if his party adopts a controversial policy to attempt to end the age of fossil fuels by keeping oil and coal in the ground, he will act to make that policy a reality.

"If the party decides that's the way, as the leader of the party, I'll do everything I can to make that a reality, but Canadians have been told too many things that haven't panned out for the last 20 years," Mulcair told Peter Mansbridge in an interview with CBC's The National.

"I'm going to make sure we put in place something where we internalize the environmental costs — user pay, polluter pay — those are all basic rules of sustainable development," Mulcair said. "That's what's been lacking in Canada — the political will to enforce those basic rules of sustainable development."

That policy proposal is one of dozens contained in the Leap Manifesto. Unveiled in September during the election campaign, it has supporters from labour unions and environmental organizations, but Mulcair has yet to endorse the document.

NDP Leader Tom Mulcair speaks to CBC Chief Correspondent Peter Mansbridge ahead of the NDP weekend policy convention in Edmonton 0:33

Aside from keeping oil in the ground, the manifesto calls for an end to trade deals and the reorienting of Canadian society away from consumer capitalism.

The document's policy proposals will be presented by activist Avi Lewis and debated at the NDP's national convention in Edmonton this weekend.

"I`m going to be at the debate, and I'm not going to now decide what the result of that debate will be," Mulcair said. "But I'm heartened and I'm thrilled to see the type of challenge that is put before us by some of our party members."

Watch Peter Mansbridge's full interview with Tom Mulcair on CBC's The National tonight at 10 p.m. on CBC Television (9 p.m. ET on CBC News Network).