Susan Davis

USA TODAY

WASHINGTON — The U.S. Senate defeated a bill to authorize construction of the Keystone XL oil pipeline, delivering a blow to Sen. Mary Landrieu, D-La., by members of her own party.

"I came here 18 years ago fighting to get here, fighting to stay here,'' Landrieu told reporters after the vote, "And I'm going to fight for the people of my state until the day that I leave. I hope that will not be soon.''

The bill failed to overcome a 60-vote threshold for passage by a narrow 59-41 decision. All 45 Republican senators voted for it, but Landrieu could not clinch the necessary last Democratic vote.

Thirteen Democrats voted with Landrieu, including outgoing Sens. Mark Begich of Alaska, Kay Hagan of North Carolina, Mark Pryor of Arkansas, and John Walsh of Montana. Additional Democratic votes came from Michael Bennet of Colorado, Tom Carper of Delaware, Bob Casey of Pennsylvania, Joe Donnelly of Indiana, Heidi Heitkamp of North Dakota, Joe Manchin of West Virginia, Claire McCaskill of Missouri, Jon Tester of Montana, and Mark Warner of Virginia.

Landrieu is locked in a Dec. 6 runoff against GOP Rep. Bill Cassidy. The pipeline vote has become a political issue in the race, where the state's oil and gas industry is supportive of the pipeline's construction and both candidates are avid supporters. The 1,200-mile proposed crude-oil pipeline would help connect existing pipelines from Canada to the Gulf Coast.

Both lawmakers used the pipeline vote to flex their legislative muscle and clout on Capitol Hill ahead of the runoff. "The race is not over in Louisiana. She has not given up, we have not given up on her behalf," said Senate Majority Leader Harry Reid, D-Nev.

Landrieu had been confident she could secure the 60 votes necessary to pass the bill, but public vote counts had the bill stalled at 59 votes Tuesday afternoon. "I don't expect it to fail," Reid said early Tuesday, but he cautioned: "I don't know what's going to happen."

The House passed mirror legislation last week, sponsored by Cassidy, who is favored to win the Senate race because of the conservative lean of the state.

If Landrieu had succeeded, it was likely to be more of a political exercise because White House spokesman Josh Earnest made clear the president does not support the bill, suggesting a likely veto if it had hit his desk. "It certainly is a piece of legislation that the president doesn't support because the president believes that this is something that should be determined through the State Department and the regular process that is in place to evaluate projects like this," Earnest said.

For the first time since 2006, Republicans will control Congress when they take over the Senate in January. They vowed to bring it up again if the Senate failed.

Incoming Senate Majority Leader Mitch McConnell, R-Ky., said the GOP-controlled Congress will take it up again next year. "The Senate will act again on this important legislation, and I look forward to the new Republican majority taking up and passing the Keystone jobs bill early in the new year."

Republicans will control at least 53 seats next year, and 54 if Cassidy defeats Landrieu.

Liberal Democrats and environmentalists oppose the pipeline as anathema to the cause of reducing global carbon emissions. "We feel that this pipeline is part of the unquenchable thirst for oil that's destroying our environment," said Sen. Patrick Leahy, D-Vt.

Republicans counter that it will spur job growth. The pipeline has been delayed for six years and is under review at the State Department. The president has previously said he wants that review to conclude before making a decision. Congress may try again to force his hand next year, but neither chamber has enough support to override a veto.

Sen. John Hoeven, R-N.D., the GOP co-sponsor of the bill, said he would consider attaching the pipeline authorization to a broader energy package or spending bill next year "that the president will not want to veto."

Contributing: Deborah Barfield Berry