Senator Mary Landrieu, of Louisiana
© Manuel Balce Ceneta/AP Senator Mary Landrieu, of Louisiana.
Led by a Louisiana Democrat and North Dakota Republican, senators pressure White House to build controversial pipeline

Barack Obama faced a new challenge on the controversial Keystone XL pipeline on Thursday when Democrats and Republicans in the Senate introduced a bill taking the decision out of his hands.

The bill, introduced by Louisiana Democrat Mary Landrieu and North Dakota Republican John Hoeven, would bypass Obama, authorising immediate construction of the 1,660-mile pipeline.

The two senators said they were hoping for a vote as early as next week. Landrieu said she hoped to "greenlight construction of the pipeline immediately". The senators claimed they had the support of all 45 Republicans and 11 Democrats.

But it was unclear whether there would be a binding vote on the bill, or whether the senators would gather the 67 votes needed to over-ride a likely veto from the White House.

The bill introduced on Thursday reflects growing frustration from Keystone supporters in Congress at the Obama administration's repeated delays of the project. The administration announced another indefinite delay last month.

Six of the 11 Democrats supporting the bill - including Landrieu - are up for re-election, and several face tough battles in conservative and oil-producing states.

Landrieu has come under fire from her Republican challengers over her failure to get the Keystone project moving. "The construction of the Keystone pipeline is very important," she said on Thursday. "It is time to stop studying and start building."

The Louisiana Democrat, who recently took over the Senate energy committee, has been pressing the Senate majority leader, Harry Reid, for a vote on Keystone.

Reid, who has expressed concerns about the environmental impacts of the Keystone, has indicated he would support a non-binding vote that would not have any legal effect.

That would avoid any showdown with the White House while providing cover to endangered Democrats, like Landrieu.

The White House called on the Senate to steer clear of Keystone, and said the decision would be made pending a State Department review - which has been delayed by Nebraska court decisions.

"We believe that this has to be run by the book, outside of politics, and that's the way it's being run," White House spokesman Jay Carney told reporters.

But Landrieu and other vulnerable Democrats said they were facing growing pressure. "Many Democrats, like myself, believe this pipeline should have been built some time ago, so we are frustrated with the slowness of the process," she told reporters.

In addition to Landrieu, the Keystone bill was supported by North Carolina's Kay Hagen, Arkansas's Mark Pryor, Alaska's Mark Begich, Montana's John Walsh and Virginia's Mark Warner. All are up for re-election.

Democratic supporters of the pipeline in the Senate wrote to Obama last month urging him to approve the project. They are targetting a handful of other Democrats this week to try and get the votes to overcome a veto.

Reid told reporters on Thursday he was largely confident of a deal. "There's a 70-80% chance we can work something out on Keystone," he said.

Republicans, however, were pushing for a binding vote, and are holding hostage an energy efficiency bill that offers a rare chance of getting environmental measures through Congress.

The Senate minority leader, Mitch McConnell, said Republicans would not accept a non-binding vote on Keystone.