A bill for the Keystone XL oil pipeline failed to pass in US congress yesterday by just one vote.
The final result was 59-41 in favour of the bill, but a majority of 60 was needed for it to go ahead. Some 45 Republicans and 14 Democrats supported the plan.
The Republicans are mostly in favour of the proposal because of the economic benefits and job creation they believe would come out of it, while many Democrats are against the plan because of the damage it could cause to the environment.
WHAT IS THE KEYSTONE XL EXTENSION?
A privately financed project, the $7bn (£4.5bn) building cost would be split between Calgary-based energy company TransCanada and other oil shippers.
The 1,179 mile pipeline would carry tar sands oil from the Canadian county of Alberta down to Nebraska in the US. There, it would join up with a pipe already being built to carry the oil down to Texas, from where it will be exported.
If it went ahead, the pipeline route would still start and finish in the same location, but it would take a more direct route with a wider diameter, transporting close to a million barrels of oil from the oil sands of Alberta to the refineries in Steele City each day.
The map below shows how the Keystone XL diversion (red) would compare to the current route (blue). If you're on a mobile or tablet, swipe to the right of the image viewer to scroll down the page.
WHY IS IT CONTROVERSIAL?
The Keystone XL extension was first proposed in 2008, and was approved by the National Energy Board of Canada in September three years later.
Many Republicans have criticised the Obama administration for its delay in deciding whether or not to go ahead with the pipeline since then, but Democrats and environmentalists argue that the pipeline will add to carbon emissions and contribute to global warming.
In fact, Obama has already opposed it once – in 2012, he rejected the application amid protests about the pipeline's impact on Nebraska's environmentally sensitive Sand Hills region.
TransCanada Corporation reacted by changing the original proposed route of Keystone XL to minimize "disturbance of land, water resources and special areas"; the new route was approved by Nebraska Governor Dave Heineman in January 2013.
But this still was not enough to persuade most Democrats that the new route was successful, yesterday's result proved. The plan could still go ahead – at present the Senate is controlled by the Democratic Party, but Republicans will control the Senate from January next year.
They have already vowed to approve the bill once they take over, with representatives describing getting the pipeline approved as one of their priorities.