A lot is riding on British Petroleum as crews work to carry out the 'top kill' maneuver.
The technique involves shooting thousands of pounds of heavy mud into a five-story stack of pipes to clog the well.
The feds and BP continue to clash on how to handle cleanup efforts.
Last week, the Environmental Protection Agency told British Petroleum to stop dumping a chemical dispersant into the water, calling it a health hazard.
Experts now say nearly 130 million gallons of crude oil have spewed into the ocean waters.
Scientists estimate the oil now covers more than 1,400 square miles, that's bigger than Maryland and Delaware combined.