NDP leader Jagmeet Singh declined on Thursday night to categorically state that the fate of the Trans Mountain pipeline expansion would be part of any post-election negotiations between NDP MPs and a potential Liberal minority government.

Earlier on Thursday, the NDP announced its "priorities" for the next Parliament, pointing to six areas in which it would like to see the federal government act. Neither the existing Trans Mountain pipeline, which the federal government purchased last year, nor the expansion projection, which the federal government has approved, were mentioned.

"I've been really clear on this. I am very much opposed to this (TMX) project. I've been opposed to it. I'll be opposed to it tomorrow and I'll continue to work against that, for sure," Singh said after the French-language leaders debate on Thursday night when a reporter asked him whether the pipeline would be a condition in any negotiations.

When the reporter followed up, Singh repeated that, "This is something that I'm opposed to, so it's very clearly against what I believe in."

Singh's answer to a third question was more ambiguous, but a second reporter returned to the subject, again asking Singh for clarity.

"So I made it really clear, our six priorities — and that includes making sure we work on the environment, making sure that we tackle the environmental crisis — that's something that's really important to me and that means reducing our emissions and ending fossil fuel subsidies," Singh said. "So that's going to be, absolutely, a part of our serious discussions we're going to have in order for us to move ahead with anyone. What we made really clear is, the environment's a priority. I am opposed to the Trans Mountain pipeline and I made that very clear...

"The owning is something that they have right now and I want to work on ensuring that we are as responsible as possible with moving forward with an asset that I would not have bought," he said. "Moving forward, I can say I'm very much opposed to the expansion and I've been very clear on that and I continue to be clear on that."

NDP Leader Jagmeet Singh and Green Party Leader Elizabeth May are asked if they could support a minority government that plans to build the Trans Mountain pipeline expansion. 2:12

The Greens and New Democrats have been jockeying to explain what they would do in the event of a Liberal or Conservative minority government.

Singh has previously said that he would not support a Conservative government under any condition. May has said she would not support any government that wanted to move forward with the Trans Mountain pipeline expansion, a position she repeated when asked Thursday whether a pipeline would be a "deal breaker" for her party's backing of any minority government.

"Yes, of course, but it's not nearly enough.

"Of course you can't build new pipelines and hope to reduce greenhouse gases; of course you can't keep fossil fuel subsidies flowing and hope to avoid the disaster that awaits us," if global temperatures rise more than 1.5 C, she said.

"Yes, you have to cancel the Trans Mountain pipeline, yes you have to keep carbon taxes, yes you have to get rid of fossil fuel subsidies, and guess what? The totality of that is not near enough."