The Senate voted 62-36 on Thursday to approve construction of the Keystone XL pipeline, escalating the fight between Republicans and President Obama over the long-stalled project at the heart of debates over climate change and energy security.
Defying a veto threat, nine Democrats joined 53 Republicans in favor of green-lighting TransCanada's $8 billion pipeline to bring crude oil from Canadian oil sands to refineries along the Gulf Coast.
The tally is five votes short of what's needed to overcome a threatened veto from Obama, who says Congress should not circumvent his administration's ongoing, six-year review of the project.
But even before the law reaches Obama's desk, lawmakers must reconcile the Keystone legislation the House approved this month with the Senate version, which was amended during the nearly month-long floor fight.
Sen. Lisa Murkowski, the top Republican on the Senate Energy and Natural Resources Committee, told reporters that the amendments were relatively noncontroversial and she's hopeful the House would "look and say, 'We can live with this.' and just take the Senate bill."
A House GOP leadership aide said discussions on how to proceed are underway, while GOP Sen. John Hoeven, the lead sponsor of the bill, similarly said that sponsors have already been in talks with the lower chamber.
While the bill faces a veto threat, the project will remain at the center of the energy debate on Capitol Hill. Hoeven has said pipeline-approval language could be attached to federal spending legislation or other must-pass bills.
At a press conference in the Capitol on Thursday, Hoeven said Republicans "hope the president will join with the Congress ... and, most importantly the American people, and approve this legislation as part of building an energy plan for this country."
Thursday's vote capped nearly a full month of Senate debate over the pipeline and a suite of proposed amendments in the Senate's widest-ranging battle over energy policy in years. Lawmakers agreed to amendments including an affirmation that climate change is real and not a hoax, and a pared-back version of energy-efficiency legislation sponsored by Republican Sen. Rob Portman of Ohio and Democratic Sen. Jeanne Shaheen of New Hampshire.
Debate on Keystone has offered the newly minted GOP majority a chance to tout what Republicans describe as the party's pro-jobs and pro-energy agenda, while at the same time taking aim at the administration for failing to make a "national interest" determination on the project after years of review.
The Democratic leadership, meanwhile, has used the debate to warn that construction of the pipeline could pose major environmental risks and slam Republicans for choosing to elevate a project that many Democrats say would create only a small number of, largely temporary, jobs at the behest of a Canadian corporation.
"This is the only time in the history of the Senate that we have given such a big hug and kiss to a company, any private company, American or foreign," Senator Barbara Boxer of California said ahead of the final vote on Thursday.
"A trail of misery follows the tar sands," Boxer added.
In a show of unity in opposition to the new Republican majority, Democrats blocked a key vote to advance the pro-KXL legislation on Monday, citing their anger at Republicans for stifling debate on a slate of Democratic amendments as their reason.
Tensions between Democrats and Republicans that surfaced during the debate likely offer a preview of what is to come as the new Congress continues.
The debate has also provided an early test of Senate Majority Leader Mitch McConnell's ability to keep his conference in line and on message. McConnell has pledged an open-amendment process and a return to regular order. The majority leader ultimately allowed a number of votes on contentious measures offered up by Democrats designed to put Republicans on the record on the existence and causes of climate change.
Despite Senate passage of the pipeline on Thursday, Keystone XL's future remains unclear.
Obama has sounded increasingly skeptical of the project's merits in recent weeks.
At an end-of-the-year press conference, the president downplayed the pipeline's potential to create jobs, said it would not lower gasoline prices, and warned that it could add to climate change.
"Now, the construction of the pipeline itself will probably create a couple thousand jobs"¦. But when you consider what we could be doing if we were rebuilding our roads and bridges around the country ... we could probably create hundreds of thousands of jobs, or a million jobs. So if that's the argument, there are a lot more direct ways to create well-paying American construction jobs," Obama said.
The president has pledged not to approve Keystone XL if it significantly adds to atmospheric levels of carbon dioxide.
A State Department review of the pipeline concluded that the pipeline would have only a minimal environmental impact, but Obama continues to raise concerns over the potential for Keystone to worsen global warming.
"I want to make sure that if, in fact, this project goes forward, that it's not adding to the problem of climate change, which I think is very serious and does impose serious costs on the American people," the president said during his December press conference.
The State Department paused its review of the project in April, citing legal uncertainty over the pipeline's route through Nebraska. A Nebraska Supreme Court ruling handed down in early January, which green-lighted the project's path through the state, however, restarted the State Department process.
Secretary of State John Kerry must still weigh in on whether he believes the pipeline is in the national interest.
But Obama will ultimately have the final say.
This story is breaking and will be updated.
Jason Plautz contributed to this article