Alberta's NDP premier has a message for anyone in her government who is thinking of going to British Columbia to campaign for the New Democrats in that province's election: Think again.

The B.C. NDP is locked in a tight election campaign and one of the party's key planks is opposition to the Trans Mountain pipeline expansion from Alberta through B.C.

It's fairly common for members from different provincial wings of the same party to help in each other's campaigns.

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But Premier Rachel Notley says it would be difficult for anybody who works for her government to support candidates that oppose a project so crucial to Alberta's interest.

The B.C. Liberals are seeking re-election after supporting the pipeline, while the B.C. Greens also oppose it.

Critics say the pipeline will mean increased tanker traffic off the West Coast and fear it will lead to further expansion of Alberta's oilsands.

"It's difficult for one to be working for our government and also supporting candidates who would be opposed to the successful construction of the Kinder Morgan pipeline," Notley said Thursday.

"We see that as being critical to our economic prosperity and growth in this province. That is the message that has been delivered and I trust that people will follow it."