BP sharply reduced its estimate on Monday of how much oil it is siphoning off each day from a ruptured well in the Gulf of Mexico that has been spewing oil for a month and threatening ecological disaster.

The British-based energy giant said the oil captured on average by a mile-long siphon tube was 2,010 barrels (84,420 gallons/319,500 liters) per day in the six days before May 23, less than half the up to 5,000 barrels (210,000 gallons/795,000 liters) per day the company estimated it had been capturing. At times the capture was as low as 1,360 barrels per day (57,120 gallons/216,200 liters).

The oil group believes about 5,000 barrels have been leaking every day, although some experts have given significantly higher estimates for the size of the leak.

The lower estimate came as two members of U.S. President Barack Obama’s Cabinet were to visit the fouled Gulf Coast on Monday to keep pressure on BP in hopes of averting a looming environmental catastrophe.