US House Speaker John Boehner signed the bill Friday approving the Keystone XL pipeline between Canada and the United States, sending it to President Barack Obama who has vowed a veto.
"The Keystone XL pipeline is a good idea for our economy, and it's a good idea for our country," Boehner said, surrounded by Republican lawmakers at a ceremony intended to put pressure on the president to sign the controversial measure.
"To the president, I'd say this: 'Do the right thing, sign this bill and help us create more jobs in America and create a healthier economy,'" Boehner said.
Obama has announced he would veto the bill, which passed Congress Wednesday, because it seeks to short-circuit the established administrative review process. The review has dragged on since builder TransCanada first applied for its permits six years ago.
The multi-billion-dollar pipeline would transport crude from Alberta's oil sands and across several US states, joining an existing pipeline network that would bring the oil to refineries along the Gulf Coast.
Obama has expressed environmental concerns about Keystone and has not yet said whether he would ultimately approve the project.
The US Constitution gives the president 10 days, excluding Sundays, to act on recently-passed legislation, or the bill automatically becomes law.
Should Obama reject the measure it would be his first veto against the newly-empowered Republican Congress.
Many Democrats and environmentalists warn of the project's potential oil spill risks. They also have broadly denounced provisions which exclude TransCanada from certain fees and taxes as a "giveaway" to a foreign company.
US Republicans, backed by Canada's Conservative government, argue that Keystone is a job generator that would boost American energy security and increase oil transport safety.
"We're hoping common sense will prevail here," Senate Majority Leader Mitch McConnell said at the ceremony.
Lawmakers were joined by the head of North America's Building Trades Unions, Sean McGarvey, who also urged Obama to "put our men and women back to work."