Federal NDP Leader Jagmeet Singh is refusing to take sides in the British Columbia-Alberta pipeline feud.

Environmental policy resolutions are set to take up a large amount of real estate at the party's convention in Ottawa this weekend.

But Singh wouldn't take the side of either of the NDP premiers currently at odds over the proposed expansion of the Kinder Morgan Trans Mountain pipeline.

Instead, he opted for diplomacy.

"Premier Notley is doing exactly what she promised to do," Singh told CBC Radio's The House. "Premier Horgan is doing exactly what he promised to do."

A few weeks ago, B.C. Premier John Horgan proposed restrictions to bitumen shipments that would flow through the pipeline from Alberta to the West Coast. In response, Alberta Premier Rachel Notley pulled her province back from purchasing hydro and wine from their western neighbour.

With the disagreement affecting the flow of goods between the two provinces, Notley reached out to Justin Trudeau to ask for a quick resolution.

But neither Notley or Horgan have reached out to Singh to ask for his help.

"I haven't spoken to either of them on this issue," Singh admitted.

The leader of the NDP talks about the work being done this weekend at the party's convention in Ottawa. 10:29

He blamed the ongoing discord on the "sham" of an environmental review system used by the Trudeau and Harper governments.

A new review process based on science and evidence would make him more at ease when approaching issues like pipelines, he said, adding that it's the responsibility of the prime minister to restore Canadians' confidence in the environmental review process.

Singh said the expansion project shouldn't move forward until an updated environmental assessment is done.

'We need big change'

By not weighing in, Singh avoids angering either B.C. or Alberta. But sitting on the sidelines isn't what the new leader needs to do, according to some critics.

"We need big change," said Avi Lewis, one of the drafters of the divisive Leap Manifesto, which was released in 2015.

For the NDP to have a chance in the 2019 election, Lewis added, the party needs to look outside the normal policy bubble everyone expects.

"You need to excite people," he said.

Becky Bond, a senior adviser to Bernie Sanders' 2016 presidential campaign who is in town for the NDP convention, agreed.

"You actually have to propose the big solutions that are going to solve problems," she said.