WASHINGTON — Senate Democrats, by a single vote, stopped legislation that would have approved construction of the Keystone XL pipeline, one of the most fractious and expensive battles of the Obama presidency.
The vote represented a victory for the environmental movement, but the fight had taken on larger dimensions as a proxy war between Republicans, who argued the project was vital for job creation, and President Obama, who had delayed a decision on building it.
Senator Mary L. Landrieu, a Louisiana Democrat who is facing a runoff election Dec. 6, had pleaded with her colleagues throughout the day to support the pipeline, leading to a rare suspense-filled roll call in the Senate. But she was ultimately rebuffed and fell short by one. The bill was defeated with 59 votes in favor and 41 against, and Landrieu needed 60 votes to proceed.
The vote was also a reflection of how a once-obscure pipeline blew up into an expensive national political battle between environmentalists and the oil industry. Although the TransCanada company proposed the pipeline in 2005, it generated so little attention that Secretary of State Hillary Rodham Clinton was poised to approve it in 2011 with little fanfare.
But at that point, environmentalists looking to press Obama to act on climate change issues seized it as a potent symbol, leading to protests outside the White House and millions of dollars from environmentalists and the oil industry poured into political races on both sides.
The political fallout, though, affected Landrieu more than the president, at least in the near term. She was able to persuade 14 Democrats to join all 45 Republicans to support the pipeline, but 40 Democrats and Senator Angus King, a Maine independent, combined to stop the legislation.
Republicans vowed to bring back the Keystone bill as soon as they return in January, when they will hold the majority. Speaking on the Senate floor moments after the vote, Senator Mitch McConnell, a Kentucky Republican and the incoming majority leader, said that he would immediately bring up a Keystone bill when the new Senate convenes.
Senator Lisa Murkowski, an Alaska Republican who is poised to replace Landrieu as head of the Senate Energy Committee, said she believed “that the momentum we’ve gained means we’ll see progress and see this bill passed.”
Despite Landrieu cajoling and browbeating her colleagues during a private lunch — which one attendee described as “civilized but pretty contentious” — Landrieu, who has so often bulldozed her way to success, was not able to produce that elusive final vote.
Given the number of Democrats who supported the bill Tuesday, Republicans might well be able to muster a filibuster-proof 60 votes to pass the pipeline in the next Congress, but they still probably will fall a few votes short of 67, the number required to override a presidential veto.
The House, which passed the same legislation Friday, had voted multiple times to approve the pipeline. But Tuesday was the first time this year that the Senate majority leader, Senator Harry Reid, a Nevada Democrat, had agreed to hold a vote on the bill, which he had feared could hurt the reelection chances of some of his more vulnerable members.
Both Landrieu and her Republican opponent, Representative Bill Cassidy, were eager to take credit for supporting the Keystone bill back home, where their state’s economy is heavily dependent on oil-industry jobs.
Even if the Senate had passed the bill, Obama was not expected to sign it into law.