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The Republican-led U.S. House of Representatives passed a bill on Friday that would approve construction of the Keystone XL pipeline, but prospects for the Senate approving the measure were uncertain.

TransCanada Corp's controversial $8 billion pipeline would help transport crude oil from Canada to the Gulf of Mexico, but is opposed by environmentalists.

An identical bill will be considered by the Senate next week but may lack the votes to pass. The bills also could face a veto threat by President Barack Obama.