NEW ORLEANS - BP mounted a more aggressive response to the oil spill in the Gulf of Mexico yesterday as it deployed undersea sensors to better measure the ferocious flow of crude while drawing up new plans to meet a government demand that it speed up the containment effort ahead of President Obama's visit to the coast.

The financial ramifications of the disaster are growing by the day as the White House and states put pressure on BP to set aside billions of dollars to pay spill-related claims in a move that could quickly drain the company's cash reserves and hasten its path toward possible bankruptcy.

One of the actions BP took yesterday was to use robotic submarines to position sensors inside the well to gauge how much oil is spilling.

Scientists haven't been able to pin down just how much oil is leaking into the Gulf, although the high-end estimates indicated the spill could exceed 100 million gallons.

The Obama administration's point man on the oil spill, Adm. Thad Allen, yesterday said government officials think the best figures are from a middle-of-the-road estimate, which would put the spill at around 66 million gallons. That is about six times the size of the Exxon Valdez spill.

There were these developments:

_ The effort to drill two relief wells more than 3 miles below the surface to end the spill has exposed problems and questions about the regulation and safety of the process. That includes that BP took more than 12 days to begin the well because the government did not require the company to have a relief-well plan in place ahead of time.

_ Beaches in Orange Beach, Ala., where large amounts of crude and tar balls washed ashore on Saturday, were mostly clean after crews worked through the night and in the early morning clearing the oil. Clear plastic bags sat in piles, full of sand and tar balls, and some empty stretches of beach were still littered with grapefruit-sized tar patties.

_ Winds continued to blow two patchy, orange oil plumes from the spill toward the white sands of the western Florida Panhandle as skimmers worked to collect the crude before it came ashore.

The Florida Department of Environmental Protection said one of the slicks is as close as 3 miles south of Pensacola Pass, an inlet next to a stretch of the Gulf Islands National Seashore and the tourist hotels of Pensacola Beach.