A bipartisan group of U.S. senators said on Thursday they had introduced legislation to approve TransCanada Corp's Keystone XL pipeline that would link Canada's oil sands to refineries and ports in Texas.

The legislation, introduced by John Hoeven, a North Dakota Republican, and Max Baucus, a Montana Democrat, would give Congress the power to approve the project.

This month the State Department issued an environmental assessment of the line, which said the project would not cause environmental harm. The Obama administration is expected to make a final decision on the project, which has been pending for more than four years, by August or later.