By Valerie Volcovici
WASHINGTON (Reuters) - The U.S. Senate may hold a vote on a bill to approve the Keystone XL oil pipeline from Canada when it returns from recess, largely to boost support for Democrat Mary Landrieu's run-off election to retain her Louisiana seat.
Lawmakers return to Washington on Wednesday for a "lame duck" session and will try to wrap up some legislation, such as spending bills, before the Republicans take control of the Senate in the new year.
The $8 billion pipeline project would deliver heavy Canadian oil sands crude from Alberta to Nebraska and make it easier to deliver oil from North Dakota's Bakken region to the U.S. Gulf Coast. It has languished for six years awaiting presidential approval, which is needed because the pipeline crosses a international border.
A senior Senate Democratic aide said in an interview that a Keystone approval vote in the lame duck session is under consideration but no decision has been made.
Another congressional aide said the measure to approve TransCanada's pipeline could come as an amendment to a must-pass defense authorization bill.
Adam Jentleson, Senate Majority Leader Harry Reid's spokesman, did not confirm the possible vote, which was first reported by Bloomberg.
Aides say a vote on the pipeline would be intended to bolster Landrieu, chair of the Senate Energy and Natural Resources Committee.
Landrieu, seeking a fourth six-year term, faces Republican U.S. Representative Bill Cassidy in a run-off election on Dec. 6 after neither of them won more than 50 percent of the vote last week. Landrieu is one of a handful of congressional Democrats who have long supported of the pipeline.
Republicans have said they plan to push their own legislation for approval of the pipeline early in 2015.
Republican Senator John Hoeven of North Dakota said he has a bill that he plans to move and with a smattering of Democratic support expects to have over 60 votes after Republicans' decisive victories in key Senate races on Nov. 4.
Matt Dempsey, a former Senate aide currently with the industry group Oil Sands Fact Check, said the election results showed the Keystone XL pipeline enjoys "overwhelming bipartisan support."
"It's no surprise, therefore, to see Congress quickly move to end President Obama's endless delay," he said.
(Reporting By Valerie Volcovici and Richard Cowan; Editing by Ros Krasny and Steve Orlofsky)