Alberta NDP Premier Rachel Notley and in-coming BC NDP Premier John Horgan disagree.

One supports the Trans Mountain pipeline. The other does not. But in holding opposite positions each will be rewarded by their province’s voters. The losers are their provincial opponents and, most of all, Justin Trudeau.

For Notley’s Alberta, the pipleline would boost funding for NDP priorities like health care, education, ending coal and diversification. It would bring Alberta oil to Vancouver to be loaded onto tankers and sold around the world. No longer captive to the low-priced US market, Alberta oil would sell at higher prices and generate higher royalty revenue.

But a pipeline gives British Columbia little economic benefit and a big environmental risk. If there’s a tanker spill, the BC coast will take the hit. Not surprisingly, Horgan’s British Columbia NDP government will be strongly against Trans Mountain.

As long as the tone stays respectful, whenever Notley and Horgan engage the pipeline debate, each will both be rewarded with the support of their voters. Neither may be cheered by voters on the other side of the Rockies, but that’s hardly their concern.

That it’s a conflict between fellow NDP Premiers is an add-on benefit.

Out-going Premier Clark, who supports the pipeline, received generous funding from the Alberta oil patch. She was criticized for putting the Liberal Party ahead of British Columbians’ interests. Horgan’s conflict with Notley suggests the opposite.

In Alberta, the opposition demands Notley condemn her BC NDP cousins. And she is all too happy to oblige. “Mark my words,” she said recently. “That pipeline will be built.” The ambitious Jason Kenney, Minister in a government that failed to build any major pipeline, was reduced to grumbling.

Notley and Horgan profit by disagreeing. The unhappy politician is Prime Minister Justin Trudeau.

Trudeau promised to fix the National Energy Board pipeline review process – gutted by Harper – and restart pipeline reviews. But reviews were not restarted. Last summer, using Harper’s process, the NEB and Trudeau approved the Trans Mountain proposal.

Add two more items to the long and growing list of Trudeau’s deceptions.

Horgan will put up a legal fight against Trudeau’s pipeline. Horgan campaigned on that promise. He put it in his agreement with the Green Party. The Greens will hold him to account – and verify to voters if John Horgan is a man of his word.

But ultimately, the BC Premier has few legal powers over an approved pipeline. If Horgan can stop it, he wins. If construction goes ahead, it’s not his fault.

It’ll be Trudeau’s fault – alone. Had Christy Clark been re-elected, Trudeau could have slid away from responsibility by redirecting environmentalist rage at her by reminding BC voters that their Premier had endorsed the project. Not now.

When construction starts and BC’s anti-pipeline activists confront it, their picket signs and placards will squarely, completely and rightly focus blame one single politician – Justin Trudeau, the bait-and-switch politician who, against their Premier, pushed through a pipeline that risks the BC coastline.

Trudeau’s margin of majority is just 14 seats. In 2015, Liberal candidates took 15 of Metro Vancouver’s 23 seats. Now Trudeau is locked-in to a loser position – one that could cost him seats in this key NDP-Liberal battleground and be a component of his defeat in 2019.

Tom Parkin is a former NDP staffer and social democrat media commentator