VENICE, Louisiana (Reuters) - Oil from BP’s out-of-control Gulf of Mexico oil spill could threaten the Mississippi and Alabama coasts this week, U.S. forecasters said on Monday, as public anger surged over the country’s worst environmental disaster.

Government and BP officials are warning that the blown-out deepwater well feeding the catastrophic spill may not be shut off until August as the company begins preparations on a new but uncertain attempt to contain the leaking crude.

On Tuesday, President Barack Obama will hold his first meeting with co-chairs of an oil spill commission he tapped to probe the worst oil spill in U.S. history and make policy recommendations about U.S. offshore oil drilling.

The commission will be similar to those that looked into the explosion of the space shuttle Challenger in 1986 and the Three Mile Island nuclear accident in 1979.

Also on Tuesday, U.S. Attorney General Eric Holder will meet with federal prosecutors and state attorneys general in New Orleans. It will be Holder’s first trip to survey the damage before what legal experts believe will be a criminal investigation into the disaster.

U.S. officials are treating the disaster, in its 42nd day on Monday, as the country’s biggest environmental catastrophe.

Although Louisiana’s wetlands and fishing grounds have been the worst hit so far by the spill, the National Oceanic and Atmospheric Administration said moderate southerly and southwesterly winds this week may start moving oil closer to the Mississippi and Alabama coasts.

“Model results indicate that oil may move north to threaten the barrier islands off Mississippi and Alabama later in the forecast period,” NOAA said in its 72-hour prediction on the expected trajectory of the huge oil slick.

Mississippi and Alabama have escaped lightly so far, with only scattered tar balls and oil debris reaching its coasts.

But the NOAA forecast was a sober reminder that oil from the unchecked spill, broken up and carried by winds and ocean currents, could threaten a vast area of the U.S. Gulf Coast, including tourism mecca Florida, as well as Cuba and Mexico.

Following the failure this weekend of BP’s attempt to plug the spewing mile-deep well, public anger over the spill and how it occurred is growing, as tens of thousands of Gulf Coast residents face a pollution impact on their livelihoods.

A group calling itself Seize BP, which has already staged anti-BP protests, said on Monday it would organize demonstrations in more than 50 U.S. cities from Thursday to Saturday to protest the damage from the leaking oil.

The group demands that BP’s assets be immediately seized and held in trust to pay compensation for the spill triggered by the April 20 explosion of the Deepwater Horizon rig.

‘JOBS VANISHING, CREATURES DYING’

“The greatest environmental disaster with no end in sight! Eleven workers dead. Millions of gallons of oil gushing for months (and possibly years) to come. Jobs vanishing. Creatures dying,” Seize BP said in a statement.

The public anger and frustration over the spill poses a major domestic challenge for Obama, who has been forced to admit publicly that the U.S. government and military do not have the technology to plug the leaking well and must leave this to BP and its private industry partners.

Obama, who made his second visit to the Gulf disaster zone on Friday, is sending three of his top energy and environmental officials back there this week. He is trying to fend off criticism that his administration acted too slowly in its response to the spill.

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The crisis could swell into a political liability for the Democratic president as his administration and party, bloodied by bruising healthcare and economic policy debates, head toward congressional elections in November.

Louisiana’s commercial and recreational fishing industry already has been dealt a blow by the spill. Fishing boats bobbed idle on Monday at the Venice Marina in Louisiana, which would normally be a hive of activity during the long Memorial Day weekend.

“Just take a look around, it’s quiet,” marina owner Bill Butler said as he sat wistfully looking at the idle boats.

As a health precaution, U.S. authorities have closed all fishing in 25 percent of Gulf of Mexico U.S. federal waters.

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The Gulf Coast is one of America’s richest ecosystems and a vital breeding ground for a $6.5 billion seafood industry.

ULTIMATE HOPES IN RELIEF WELL

BP executives say the company will try several immediate options to try to control the leak, including the planned deployment of a containment cap in the next few days, but the ultimate solution may only lie in the drilling of a relief well that is expected to be completed in August.

The drilling of two relief wells, which began in May, is an expensive but more reliable way to intercept and cap the leaking well.

The Gulf spill has surpassed the Exxon Valdez disaster off Alaska in 1989 as the worst U.S. oil spill, with an estimated 12,000 to 19,000 barrels (504,000 to 798,000 gallons/1.9 million to 3 million liters) leaking per day.

BP is now preparing a containment cap to place on top of a lower marine riser package (LMRP), a piece of equipment that sits atop the failed well blowout preventer on the seabed.

Remote vehicles have begun cutting away pipes atop the blowout preventer to allow a tight fit with the cap, and will saw through the main riser pipe in “next day or two,” a BP spokesman said on Monday.

If the containment operation works -- and BP expects to know later this week -- then at least some of the leaking oil could be piped to the surface.