Alberta's premier says a U.S. rejection of the Keystone XL pipeline proposal would undermine the Canada-U.S. relationship.

In an interview with The Canadian Press, Alison Redford says Canada and the United States have a long history of economic integration that would be fundamentally challenged by a 'No' to the pipeline.

She says turning the pipeline down would signal that the United States no longer has faith in Canada as a trusted trading partner that has common cause with Americans.

But Redford doesn't think it will come to that.

She says she thinks the Obama administration will approve the pipeline eventually, and both countries will soon look back on the contentious debate as a time for honest discussion about how best to expand the North American economy.

She says Alberta is raising its bar for environmental performance, and is re-orienting its economy to focus not just on oilsands but also on sustainable energy.