BP is ready to switch caps at the wellhead of the gushing Gulf of Mexico leak as part of an effort to capture more of the oil, the top official overseeing the spill response said on Thursday.

Retired U.S. Coast Guard Admiral Thad Allen said BP and government officials would decide in the next 24 to 48 hours whether to switch the cap, which would lead to a short-term free flow of oil. The switch also would increase BP's siphoning capacity to 80,000 barrels a day.

The White House is sending BP Plc a list of questions about its efforts to cap a gushing oil well in the Gulf of Mexico and is ordering the company to respond within 24 hours, a U.S. official said on Thursday.

The letter from the White House comes after Retired U.S. Coast Guard Admiral Thad Allen, the top official overseeing the spill response, said BP is ready to switch caps at the wellhead as part of an effort to capture more of the oil.