British Columbia NDP Leader John Horgan and Green Party Leader Andrew Weaver were clearly on a roll last week at a celebratory news conference that formalized what they promised would be a four-year collaboration.

And it was the tag-team response to questions about the Kinder Morgan pipeline expansion that most revealed how Horgan and Weaver might handle the political problem with Alberta and fellow NDP Premier Rachel Notley.

"I haven't spoken to Rachel directly," said Horgan, whose past dealings with the Alberta premier put the two on a first name basis.

Horgan said the Alberta premier, who is pushing hard for Kinder Morgan, is rightly waiting until the new government in B.C. is in place before reaching out.

"When that happens, we'll have that conversation," he said.

It was all very nice. But the gentle tone and tenor didn't last very long.

'Mark my words,' Notley vows

For her part, Notley spent a good deal of time challenging the premise that a Green/NDP government in B.C. can stop the pipeline.

On Tuesday, the Alberta premier vowed at a news conference: "Mark my words, that pipeline will be built, the decisions have been made."

When a reporter asked later that day about Notley's pronouncement, Green Party Leader Andrew Weaver laughed out loud as Horgan lobbed the hot potato his way.

Former B.C. premier and federal cabinet minister Ujjal Dosanjh says without the Greens the pipeline issue would have been easier to deal with. (Twitter)

"You wanna go?" Horgan asked Weaver at their news conference.

Weaver then unleashed a tirade, lecturing Notley for not understanding the realities of the new economy.

"For Ms. Notley to tell British Columbia that somehow chasing the 20th century is the way for our future is not a good sign for her and her economy in Alberta," Weaver said.

"Frankly, I think she should get with the program and embrace the 21st century as well."

Ujjal Dosanjh, former B.C. premier and one-time federal cabinet minister, knows both Notley and Horgan personally, and calls them "down-to-earth pragmatic people."

Dosanjh hired Notley as an aide when he was attorney general in B.C. Notley and Horgan worked together in 1996 as political staffers for the NDP government of the time.

Deal easier with Greens

Despite the B.C. NDP opposition to Kinder Morgan during the election campaign, Dosanjh thinks things would be much different today had the NDP won the election outright.

"Without the Greens it may have been an easier relationship and issue to deal with," said Dosanjh.

Dosanjh said he believes Horgan would be the first person to acknowledge the need for economic development. And in this case, Dosanjh said, that points towards a new pipeline.

"I don't know what will eventually happen, but I think in his heart, he may realize that Kinder Morgan can't be prevented," he said. "At some point it will happen, unless the oil goes completely out of our lives."

For now, the pipeline dispute between Alberta and B.C. is simply a war of words between former political allies.

But opposition to the Kinder Morgan project shows no sign of abating.

Eriel Deranger from the Athabasca Chipewyan First Nation is a well-known environmental activist in Alberta working to stop the Kinder Morgan expansion. She has taken part in anti-pipeline demonstrations in B.C. and plans to continue.

Making 'brash' comments

For her, Alberta's climate leadership plan does nothing to mitigate the impact of ramping up oilsands production.

Notley's resolve to see the pipeline built is a disappointment to an activist who first saw Notley as an ally.

Eriel Deranger of the Athabasca Chipewyan First Nation with retired South African Archbishop Desmond Tutu and Chief Allan Adam in Fort McMurray in 2014. (CBC) "Our leader who once sided with First Nations, that once sided with the climate, is making such brash comments," said Deranger. "'Mark my words, the pipeline will be built,' it just doesn't match what she was elected on, at all."

Dosanjh thinks Kinder Morgan will proceed if the courts don't stop the project. He agrees with Notley that a coastal province like B.C. can't prevent an landlocked province like Alberta from accessing the ocean.

"Environmentalism is somewhat of a non-partisan issue in B.C.," Dosanjh said, who pointed out it was former premier Gordon Campbell who introduced the carbon tax in that province in 2008.

"British Columbia is a very green province," said Dosanjh. "I can understand the intensity of the issue. It's the province of David Suzuki, it's the province of very prominent environmental activists."

Despite the differences between Horgan and Weaver on one side and Notley on the other, Dosanjh thinks political connections established more than two decades ago can pay off now, in ways they can't even imagine.

"Those relationships can go a long way," said Dosanjh. "They may lead you to a more pragmatic yet progressive solution, that might otherwise not even happen."