BP is preparing for a new attempt to curb the leak from an oil well in the Gulf of Mexico.
The company now plans to lower a containment cap over the well, in the hope that most of the oil can be piped to the surface.
Undersea robots will be used to cut a pipe and position the device.
The fresh tactic follows the failure of an attempt to stem the leak by pumping mud into the well.
BP said the new technique could initially increase the flow, and success is not guaranteed.
More than 110km of coast may be affected
On Sunday, the White House said the Gulf oil spill was the worst environmental disaster the United States has faced.
An estimated 12,000 - 19,000 barrels are leaking into the Gulf every day. More than 110km of the coastline of Louisiana are reported to be affected.
BP has spent more than $US940 million so far in trying to contain the disaster.
Eleven rig workers died when the Deepwater Horizon rig exploded on 20 April. It sank two days later.