(CNN) -- Here are the latest developments involving the BP oil spill in the Gulf of Mexico:
Obama Administration questions BP's estimate of oil spill rate: "BP has a financial interest in these numbers. They will pay a penalty based on the number of barrels per day," Carol Browner, Obama assistant on energy and climate change, said.
The U.S. Fish and Wildlife Service and the United States Coast Guard will transport recovered oiled birds, including brown pelicans and a northern gannet, from the Ft. Jackson Wildlife Rehabilitation Center in Ft. Jackson, Louisiana to Egmont Key National Wildlife Refuge at the mouth of Tampa Bay, Florida, where they will be released into the wild on Sunday.
A team of oil spill experts were on standby in the United Arab Emirates, ready to help in the Gulf of Mexico cleanup efforts if called to do so, said Craig Buckingham of the Abu Dhabi National Oil Company.
Sen. Mary Landrieu, a Democrat from Louisiana, said Saturday night that BP should immediately invest $1 billion to protect marshes, wetlands and estuaries.
An independent contractor supplying workers to clean up an oil spill on the Gulf Coast denied that his company sent more workers to Grand Isle, Louisiana, on Friday just because Obama was going to visit that site. Donald Nalty of Environmental Safety and Health, hired by BP to supply clean-up workers, said, "I had no idea about the president" and that his company decided several days before it knew of Obama's visit that it would send 400 workers to Grand Isle on Friday.
Interior Secretary Ken Salazar said that Bob Abbey would become acting director of the troubled Minerals Management Service even as he retains his role as director of the federal Bureau of Land Management. Salazar said previous director Elizabeth Birnbaum resigned, but two sources said she was fired. Abbey will begin to manage the reorganization of the Minerals and Management Service into three separate agencies. Salazar has unveiled plans to divide the agency's energy development, enforcement and revenue collection divisions, saying they have "conflicting missions."
Obama said the spill had sparked the "largest cleanup effort in U.S. history."
The oil spill
BP Managing Director Robert Dudley said Sunday that after failing to plug the Gulf of Mexico oil leak, the next step is try to reduce the amount of oil spilling into the ocean while drilling a relief well intended to halt the leak by August.
Dudley said that oil would continue to flow "for a while" from the leaking well, and the company would strengthen efforts to
keep it from reaching Gulf beaches.
President Barack Obama's assistant on energy and climate change, Carol Browner, said the oil spill is "probably the biggest environmental disaster we've ever faced in this country."
BP's "top kill" attempt to stop the flow of oil from a ruptured well in the Gulf of Mexico failed, the company's chief operating officer said Saturday.
The next option will be to place a custom-built cap known as the "lower marine riser package cap" over the leak, Doug Suttles said. BP crews were working Saturday to ready the materials for that option, he said.
Subsea dispersants will be used in next attempt to stop flow from breached well, the Coast Guard said. "The real solution, the end state, is a relief well," Coast Guard Rear Adm. Mary Landry said.
Obama ordered Interior Secretary Ken Salazar, Environmental Protection Agency Administrator Lisa Jackson and NOAA Administrator Jane Lubchenco to return to the Gulf of Mexico as part of the federal response to the oil spill.
The spill is the largest in U.S. history. Government scientists said Thursday that as many as 19,000 barrels (798,000 gallons) of oil were spewing into the ocean every day, making this disaster perhaps twice the size of the 1989 Exxon Valdez spill.
At least two more oil spill cleanup workers have been hospitalized after feeling ill on the job, according to local shrimpers who are assisting in the recovery effort along the Gulf Coast. The workers complained of nausea, headaches and dizziness after low-flying planes applied chemical dispersants within one mile of operating cleanup vessels.
Some people involved in cleaning up the oil spill "clearly" have become sick, but the reasons are not yet clear, Suttles said earlier Saturday.
Seven oil spill recovery workers who were hospitalized in New Orleans, Louisiana, after complaining of feeling ill were properly trained and had protective gear on, according to the federal on-scene coordinator for the oil spill response effort.
Landry said workers were treated for several symptoms, including headaches, nausea, vomiting and shortness of breath. Safety officials from the Coast Guard, BP and the federal Occupational Safety and Health Administration have responded.
BP said it has provided spill recovery workers with protective equipment, such as suits, steel-toed boots, gloves, hard hats and safety glasses. In addition, BP said, workers are conducting about 250 air-quality tests a day. They also are testing workers for exposure to irritants and other substances that could be harmful, BP said.
The commercial and recreational fishing closure is now 60,683 square miles, which is about 25 percent of the Gulf of Mexico exclusive economic zone, according to the National Oceanic and Atmospheric Administration. The closure went into effect at 6 p.m. ET Friday.
Images from the massive BP oil spill have prompted tourists to go to other destinations this Memorial Day weekend.
Hotels in Florida, Alabama and Mississippi are using everything from "beach cams" and money-back guarantees to constant updates on their websites to get the word out that their beaches are clean and open for business.
In Louisiana, hotels catering to sport fishermen are seeing a falloff in bookings, but that's been offset by the masses of recovery workers, BP employees and journalists who have poured into the area.
Oil prices rose Friday for the third day in a row, as traders anticipate that a six-month moratorium on new offshore drilling permits and other responses to the spill could mean supply decreases in the long term.
Prior to the scrapping of the "top kill" effort, BP said Friday its costs have totaled $930 million to date. That includes expenditures on the spill response, containment, relief well drilling, grants to the Gulf States, claims paid and federal costs.