VENICE, Louisiana (Reuters) - President Barack Obama scheduled a Sunday visit to the U.S. Gulf Coast to ramp up efforts to control a huge growing oil slick threatening major environmental and economic damage to four coastal states.
Obama, who has promised to use every resource to try to avert what appears to be a looming environmental disaster, will hope to deflect criticism that perhaps his administration could have been quicker off the mark to react to the oil spill.
The Coast Guard and forecasters said the 130-mile by 70-mile slick, swelled by oil gushing unchecked from a ruptured deepwater well in the Gulf of Mexico off Louisiana, was being blown northwards toward land by winds.
In the first sign that the spill has affected U.S. offshore energy production, the Minerals Management Service said on Saturday two U.S. offshore Gulf of Mexico production platforms had been shut down and a third was evacuated as a precaution. Further shutdowns were possible, it added, but the output affected so far was very small.
Obama's administration is piling pressure on London-based BP Plc, the owner of the blown-out well, to do more to plug the flow of oil and contain the spreading slick. The cost of the cleanup, and the potential damage that could be inflicted by the spill, are estimated in billions of dollars.
BP chief executive Tony Hayward was traveling to the U.S. on Saturday to oversee the emergency cleanup operation.
Coastal communities, wildlife refuges, fisheries, tourism and beaches from eastern Louisiana to northwest Florida are all at risk from the spreading slick, which BP, the Coast Guard, the U.S. military and volunteers have been trying desperately to disperse, block and stem both above and under water.
"This thing is still growing and the wind is moving it northward," Coast Guard Petty Officer David Mosley said. But he said the Coast Guard could not so far confirm reports from the public that the oil had reached land.
Crude oil is pouring out at a rate of up to 5,000 barrels (210,000 gallons or 795,000 liters) a day, according to government estimates, but experts said the quantity of crude escaping was difficult to measure and could be higher.
The leak, which followed a rig explosion and sinking last week, has forced Obama to suspend politically sensitive plans to expand offshore oil drilling, unveiled last month partly to woo Republican support for climate legislation.
The unified command set up to tackle the spill crisis said crews worked through the night using an underwater ROV (remotely operated vehicle) to aim thousands of gallons (liters) of dispersant at the leaking oil beneath the service.
Other options to try to cap or seal the well, or even simply reduce the oil flow, are seen taking weeks or months.
Above the surface, several hundred boats and planes were also struggling to contain the slick and the Coast Guard worked to extend long barriers of containment booms in an effort to stop the oil from soiling the shore.
But forecaster AccuWeather.com said deteriorating weather and rough seas would hamper cleanup crews this weekend.
A Reuters photographer who traveled in a plane that flew over the Louisiana coast saw some boom barriers broken up by the wind and waves, and the booms washed up on the coast.
Louisiana, Mississippi, Alabama and Florida have all declared states of emergency, and shrimpers, fishermen and local residents in several states have rushed to file lawsuits against the companies that operated the rig.
Obama, no doubt mindful of public criticism of President George W. Bush's handling of the 2005 Hurricane Katrina disaster, on Friday sent senior officials to check on the efforts to fight the slick.
In an editorial on Saturday, the New York Times said there were unanswered questions about the spill.
"The company, BP, seems to have been slow to ask for help, and, on Friday, both federal and state officials accused it of not moving aggressively or swiftly enough," it said. "Yet the administration should not have waited, and should have intervened much more quickly on its own initiative."
Obama and U.S. officials have increasingly stressed the first responsibility lies with BP. Interior Secretary Ken Salazar met with BP executives and said he told them to "work harder and faster and smarter to get the job done."
"BIG OIL ON TRIAL"
Douglas Brinkley, a professor at Rice University in Houston, said he believed the Obama administration was holding back from criticizing BP more because it needed the company to help seal the well. "Once the hole is plugged you are going to see the federal government rake British Petroleum over the coals ... Big Oil will be put on trial in the same way that Goldman Sachs is getting put on trial," Brinkley said.
BP CEO Tony Hayward promised an aggressive cleanup campaign and said BP would compensate those affected.
Officials in Louisiana's Mississippi Delta said on Friday a thin "oil sheen" had reached barrier islands. At least one bird, a Northern Gannet, was treated for oil contamination in what environmentalists fear could be a disaster for wildlife.
Off the Louisiana coast, miles and miles of boom had been laid and the plan was to place it in three lines, two lines of hard boom and a third line of absorbent boom behind that.
"That allows us multiple layers of defense against any kind of oil that gets through .... It will get slowed down," Plaquemines parish zone director Peter Hahn said in Venice.
BP, working with the Coast Guard, was also using specialized boats with oil skimming equipment. Parish authorities and private fishermen were contracted to help with the cleanup and containment effort, Hahn said.
About 6,000 Louisiana National Guard troops were mobilized and two Air Force planes were sent to spray dispersant.
LITTLE HOPE OF QUICK FIX
Experts said there was little hope BP would succeed with a quick fix to cap the well. BP hopes to use a giant funnel that would catch the oil and channel it to a tanker ship.
But that would take four weeks. If the funnel does not work, BP will have to try stemming the flow by drilling a relief well, which would take two to three months.
"At 5,000 barrels a day, in two months' time it's going to be a bigger spill than the Exxon Valdez," said Tyler Priest, director of global studies at the University of Houston's Bauer College of Business. He was making a comparison with the 1989 Exxon Valdez incident, the worst U.S. oil spill on record.
The Obama administration has said no new offshore drilling areas would be allowed until after a review of the spill.
The Gulf Coast and its marshlands are home to hundreds of species of wildlife, including manatees, sea turtles now about to nest, dolphins, porpoises, whales, otters, pelicans and other birds. The wetlands are also a stopover for millions of migrating birds.
The Gulf is also one of the world's most fertile seafood grounds, teeming with shrimp, oysters, mussels, crabs and fish. It supports a $1.8 billion industry second only to Alaska.
Shares of companies that provided services or operated the sunken drilling rig that set off the leak fell sharply as worry mounted about liability from the spill.
(Additional reporting by Chris Baltimore  and Kristen Hays in Houston, Tom Bergin  in London, Carlos Barria  in Venice, Louisiana, Phil Stewart  in Washington, Joshua Schnyer and Rebekah Kebede  in New York; Writing by Pascal Fletcher )