(Corrects to 67 from 60 the votes needed in Senate to overcome presidential veto)
By Ros Krasny
WASHINGTON May 21 (Reuters) - The White House has threatened to veto legislation pending in the U.S House of Representatives that could strip from President Barack Obama the authority to approve the controversial Keystone XL pipeline.
The Republican-controlled House is expected on Wednesday to vote on, and almost certainly approve, H.R. 3, the Northern Route Approval Act.
The bill would declare a Presidential cross-border permit is not required to approve the TransCanada Corp.'s proposed pipeline, which would carry oil sands from Canada's Alberta province to refiners in Texas.
Obama's advisers "would recommend that he veto this bill," the White House's Office of Management and Budget said in a statement of administrative policy.
Prospects for action on Keystone in the Senate, which is held by Democrats, are uncertain.
A majority of the Senate wrote to Obama in January urging approval of the project. But those 53 backers, including nine Democrats, would be far short of the two-thirds votes needed to overcome a presidential veto - 67 if all 100 members of the Senate voted.
In its statement the OMB said the House bill "conflicts with longstanding Executive branch procedures regarding the authority of the President, the Secretaries of State, the Interior, and the Army, and the Environmental Protection Agency administrator."
It added that the State Department "is working diligently to complete the permit decision process" for Keystone, making the bill "unnecessary."
A decision on the pipeline has been pending for over four years. The project is strongly supported by much of the energy industry as a boost to North American oil security, and by some unions as a driver of job creation.
Environmental groups say the 830,000-barrel-per-day pipeline would raise greenhouse gas emissions and lock the United States into oil dependence for decades into the future. (Reporting by Ros Krasny; Editing by Bob Burgdorfer)