Canadian pipelines have become a hot issue in the domestic politics of both Canada and the United States, and there is a lot more to come.

American environmental activists and their Canadian colleagues joined forces with Canadian aboriginal leaders in creating such a storm over the Keystone XL pipeline that U.S. President Obama was forced to delay the massive project, which planned to take oil from Alberta to the Texas coast.

Once again, the two sides are bringing the big battalions together in opposition to the Enbridge corporation's proposed Northern Gateway pipeline, which would transport bitumen from Alberta across British Columbia to coastal ports.

The product would then be shipped to new customers in China and elsewhere in Asia aboard gigantic oil tankers.

(That, by the way, would mean cancelling a long-standing moratorium on tanker traffic along the pristine B.C. coast, which is a separate environmental issue on its own.)

Canadian oil producers, not to mention taxpayers, stand to lose as much as $70 billion a year in revenue if they can't figure out a way to get Alberta oilsands products out of the province to world markets.

Public hearings into the proposed project begin this Tuesday, and a solid slate of Aboriginal tribes across Alberta and B.C. are lined up and ready to open fire.

Even such luminaries as American actors Robert Redford and Kevin Bacon are joining in the opposition to the all-Canadian pipeline, which Prime Minister Stephen Harper says raises some serious questions about foreign political interference.

Meanwhile, next week, the second stage of the race to decide who will carry the Republican banner in next fall's U.S. presidential election takes place at the New Hampshire primary.

And with the American economy suffering a serious slowdown, Republican candidates led by Mitt Romney are highly critical of Obama's decision to postpone the XL project, which would have created thousands of badly-needed American jobs.

On Sunday's edition of Question Period, we'll be all about the politics of pipelines.