The issue focused on oil pipeline construction in North Dakota. The proposed Keystone XL pipeline would carry crude from Alberta to refineries on the Texas Gulf Coast. It has become a flashpoint for climate change activists and Native American tribes.

Mr. Obama said he had ordered an environmental review of the project, which was opposed by climate activists who say it will contribute to climate change. Mr. Obama also denied climate change as a factor in his decision to reject the pipeline.

"This is not just another climate