VENICE, Louisiana (Reuters) - President Barack Obama will visit the Gulf Coast on Sunday to bolster efforts to avert an environmental disaster threatened by a huge, growing oil slick forecasters said was being driven ashore by winds.
The visit, which a White House official said would be on Sunday morning, signaled Obama was anxious to be seen paying close attention to the cleanup and containment of one of the worst oil spills in U.S. history.
No details were immediately disclosed of the locations Obama would visit.
Swelled by oil gushing unchecked from a ruptured deepwater well in the Gulf of Mexico off Louisiana, the 130-mile by 70-mile slick is imperiling wildlife refuges, fisheries and beaches across four states from eastern Louisiana to northwest Florida.
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.
His 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 operation is estimated at billions of dollars.
"Winds from the south-southeast will continue to drive the expanding oil slick in the Gulf of Mexico ashore in the Mississippi Delta region through this weekend," forecaster AccuWeather.com said on Saturday.
Local officials in Louisiana's Mississippi Delta said on Friday a thin "oil sheen" from the slick had already 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.
Gail Bishop, a spokeswoman for a task force operated by the U.S. government and BP, said the spill was closest to land at Pass-a-Loutre Wildlife Management Area near Venice, Louisiana.
"It hasn't really hit the shoreline and it seems to be drifting east," Bishop said.
As several hundred boats and planes struggled to contain the slick and disperse it with chemicals at sea, the Coast Guard scrambled to lay long barriers of containment booms in a desperate effort to stop the oil from soiling the shore.
"We have a lot of boom out there at the moment," Coast Guard spokesman Matthew Schofield told Reuters.
But AccuWeather said deteriorating weather and rough seas would hamper cleanup crews this weekend as they tried to lay more of the floating booms. Boats set out from Venice on Saturday to lay fresh lines of the orange boom.
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.
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.
Experts said there was little hope BP would succeed with a relatively quick fix to cap the well.
BP hopes to cover the well with a giant inverted funnel that would capture the oil and channel it to a tanker ship.
But that would take four weeks, by which time over 150,000 barrels could have been spilled. 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.
"You're looking at a huge disaster," Priest said.
Off the Louisiana coast, miles and miles of boom had already been laid and the plan was to place it in three lines of defense, 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.
BP on Friday said it would pay fishermen to help with the operation $2,000 a day for boats of 45 feet and over and a lesser rate for smaller boats.
"It's critical (to use local fishermen). These guys have the local knowledge. Fishermen are great," said Vince Mitchell of O'Briens Response Management, which is contracted by BP.
The Obama administration has said no new offshore drilling areas would be allowed until after a review of the spill. [ID:nN30124592] It also called on BP to commit more resources and fund the cost of the cleanup.
About 6,000 Louisiana National Guard troops were mobilized to help remove the oil and protect critical habitats. Two Air Force C-130 aircraft equipped to spray dispersant chemicals were dispatched to join the containment effort.
On Friday, Obama sent top administration officials to Louisiana to assess the situation.
'WORK HARDER AND FASTER AND SMARTER'
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."
CEO Tony Hayward promised an aggressive cleanup campaign and said BP would compensate those affected.
The undersea leak from the sunken Deepwater Horizon rig is very deep at 5,000 feet down on the sea bed, and BP has asked the Pentagon to supply underwater imaging technology and robots.
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.
"The cost to Louisiana's fishing industry could be $2.5 billion and the impact on tourism along Florida's Gulf coast could be $3 billion, estimated Neil McMahon, analyst at investment firm Bernstein.
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, Phil Stewart  in Washington, Joshua Schnyer and Rebekah Kebede  in New York; Writing by Pascal Fletcher ; Editing by Eric Beech )