Following years of legislative tussles, Congress was set Wednesday to green-light the Keystone XL pipeline transporting Canadian oil to US refineries, but President Barack Obama is pledging to veto the measure.
The House of Representatives was expected to give Congress's final seal of approval on a bill authorizing construction of the controversial project, for which permits were first sought six years ago.
The pipeline stalled as it ran into a buzz-saw of criticism from environmentalists, as well as approval delays by the Obama administration.
After numerous Republican attempts to force Obama's hand on the project, the Senate passed its version of the bill last month with bipartisan support. The House is widely expected to follow suit.
Ahead of the House vote, Senate Majority Leader Mitch McConnell hailed the bill as a "common sense" measure supported by labor unions and the American public alike.
"Construction of this infrastructure project would pump billions (of dollars) into the economy and support thousands of good jobs," McConnell said.
The legislative move would override the extended review process and ram through authorization, allowing builder TransCanada to get to work on the 1,179-mile (1,900-kilometer) pipeline that Republicans insist is a job generator that will boost US energy security.
But the White House has threatened a veto out of environmental concerns and wish for the review process to play out, a move some Republicans will no doubt use to bolster their argument ahead of the 2016 presidential race that Obama is blocking crucial job-creating initiatives.
"The president has been pretty clear that he does not think circumventing a well-established process for evaluating these projects is the right thing for Congress," White House spokesman Josh Earnest said in January.
The veto would be the third of Obama's presidency, and by far the most significant.
Overcoming a veto would require a two-thirds majority in Congress, an especially heavy lift in the 100-member Senate where Republicans hold 54 seats and would need 13 Democrats to join them.
Nine Senate Democrats backed Keystone last month.
- Benefits to US? -
The project has already proved divisive this year. Republicans made Keystone their top priority after winning full control of Congress in November's midterm elections, citing a State Department review that concluded the pipeline would generate some 42,000 construction jobs.
Many Democrats have several objections: they say oil sands produce "dirty" crude that takes more energy and water to extract and refine than conventional crude; the project is a nod to a foreign company; and just 35 of the Keystone jobs will be permanent.
"And in the end, the refined oil coming in from Canada will not benefit the American economy" as most of it would be exported, Senate Democrat Dick Durbin told the chamber Wednesday.
Various government departments have been reviewing the project to see if it would be in the "national interest."
In mid-2013, Obama said such an interest would be served "only if this project does not significantly exacerbate the problem of carbon pollution."
The State Department, in its environmental impact assessment released in January 2014, determined that Keystone would not likely alter overall greenhouse gas emissions.
Republicans argue that moving oil by pipeline releases far fewer emissions than transporting it by rail or road.
In recent weeks, taking Obama's lead, Democrats began framing the Keystone debate in terms of it being a benefit to Canadian interests.
In December, Obama explained part of his opposition to the pipeline, saying it would be "very good for Canadian oil companies and it's good for the Canadian oil industry, but it's not going to be a huge benefit to US consumers."