Keystone approval dies in the Senate

Louisiana Sen. Mary Landrieu fell one vote short of the 60 she needed to get her bill authorizing construction of the Keystone XL pipeline through the Senate tonight. Republicans, who all supported the measure, vowed to bring the bill back in January when they'll have the votes to push it through.

But Landrieu might not be there to cast her vote of approval.

Tonight's vote was part of a last-ditch effort to persuade Louisiana voters to return Landrieu to Washington. She's in a tough runoff battle with Republican Rep. Bill Cassidy, who sponsored the Keystone legislation that passed the House on Friday. The election is set for Dec. 6.

Landrieu initially said she had the votes she needed, but some of her Democratic colleagues might have been dissuaded by this morning's White House announcement that President Barack Obama planned to veto the bill if it made it to his desk. Until today, Obama had not issued his familiar veto threat, leading some pundits to speculate he might be willing to give it the thumbs up this time.

Although a State Department report said the pipeline would have minimal environmental impact, the Obama administration has not completed its review of the project. Environmentalists and clean energy advocates oppose the pipeline, which would bring oil from Canada to the Texas Gulf Coast.

The Associated Press contributed to this report.