Former B.C. Premier Christy Clark is calling out her successor, John Horgan, for what she calls an “unconstitutional” attempt to kill the Trans Mountain pipeline project.

In an interview with CTV’s Question Period, Clark echoed Alberta Premier Rachel Notley’s accusations that B.C. is illegally trying to stop Kinder Morgan’s $7.4-billion project, which has already earned federal approval.

“I think he’s breaking the law,” Clark said. “I think he is doing something unconstitutional. Alberta and British Columbia have been the best of friends in Canada for a long, long time and I don’t think you attack your friends.”

Clark added that Horgan’s response means “Canadians are losing out.”

“There are rules. It’s been approved, it’s been properly approved,” she said. “What he’s doing is trying to set up a system where it cannot get to ‘yes’ and deliberately frustrating it so the project will get cancelled. He doesn’t have the constitutional right to do that.”

Last week, B.C. said it planned to review limits on diluted bitumen shipments over concerns about a possible oil spill – a risk the province fears would spell disaster for its environment and economy.

In response, Alberta stopped talks on plans to buy electricity from B.C. Notley later announced a province-wide ban on B.C. wine imports, effective immediately.

Last week, Notley called on Prime Minister Justin Trudeau to take a stand on the issue. Trudeau has said he doesn’t plan on wading into the inter-provincial spat, but that Kinder Morgan will be built.

Clark also called on Trudeau to step in “for the good of the country.”

“If the Prime Minister wants to get into a fight with premiers, the one worth getting into is the one over Kinder Morgan,” she said. “He’s going to be in a fight either way, that’s the fight I think they should pick, and I think it’s one they would win on behalf of all Canadians.”

Time to ‘take temperature down’: McKenna

Environment Minister Catherine McKenna defended the federal government’s response and said it’s time to “take the temperature down.”

“We’ve been very clear that this project, the approval, was well within out jurisdiction, and it’s going to go ahead,” McKenna told CTV’s Question Period. “Once we make a decision, we need to show that it goes through.”

Federal officials are in closed-door talks with the B.C. government, McKenna said.

On Thursday, the federal government updated its environmental assessment process for energy projects, including a new two-year timeline to approve or deny projects and a commitment to consider Indigenous rights and health, social and economic effects.

McKenna shut down criticism leveled by some that the new regulations undermine current projects, such as the Trans Mountain pipeline.

One of those critics was Clark.

“They’re absolutely wrong,” McKenna said. “I’m not taking any lessons from former premier Clark.”

‘We mean business’: UCP Leader Kenney

Alberta Opposition leader Jason Kenney, who has previously supported Notley’s fight against the B.C. government, said he thinks it’s still the right approach, but said while Alberta means business, “we don’t need a trade war.”

The United Conservative Party Leader joined Clark and Notley in pushing for Trudeau to intervene.

“The feds could stop it tomorrow if the Prime Minister exercised leadership,” Kenney told CTV’s Question Period.

He also warned Horgan’s government that Alberta won’t forget B.C.’s actions.

“If the B.C. government is threatening to violate the constitution, the economic union, which is a central guarantee of our constitution, they can’t do it without repercussions,” he said.

Singh avoids taking sides

As tensions deepen between the two NDP-led provinces, federal NDP Leader Jagmeet Singh stopped short of taking a side, though as the federal NDP leader he is opposed to Kinder Morgan.

“What I do support is the fact that Premier Notley is doing exactly what she said, defending her economy, defending the people of Alberta, and Premier Horgan is doing exactly what he said, defending the interest of the people of British Columbia, of the coastline, and the environment,” Singh said.

He placed the blame with Trudeau for the current predicament and, like Clark, Notley and Kenney, called on the prime minister to “step up.”