The Obama administration is to reassess the route of a Canada-US oil pipeline, delaying a decision on the project by up to 18 months.
Studying a new route for Keystone XL is now expected to push the final decision past the 2012 presidential election.
The 2700km pipeline would run from Canada to the coast of Texas.
The State Department is holding public consultations on the project as the pipeline would cross the US border with Canada.
The BBC reports its handling of the $US7 billion project is already under review.
In a statement on Thursday, the department said it would assess potential alternative routes in Nebraska.
Canadian Oil Minister Joe Oliver said a US decision to delay or cancel the pipeline would not stop oil sands development in the province of Alberta.