The State Department announced Monday it is extending its review of a controversial pipeline that would expand U.S. imports of petroleum from Canadian oil sands. The delay comes amid growing concern from both the administration and congressional Democrats that the practice of extracting oil from sand is an environmentally damaging practice that emits greenhouse gases. The State Department extended its deadline for comments from federal agencies from September to mid-December. The public comment period ended at the beginning of July. A final environmental impact statement for the project is expected sometime after Dec. 15. TransCanada needs U.S. approval to construct its pipeline — called Keystone XL — from Alberta, Canada, to Texas.