The accident is also threatening to doom a historic environmental protection bill, a compromise bill introduced in the Senate designed to curb greenhouse gas emissions.

The bill, much expected both domestically and by the international community, was the result of decades' efforts by all parties to prepare the U.S. to deal with global warming.

However, the bill, which calls for offshore drilling, is now in danger as some senators are threatening to pull their support.

British Petroleum, which operated the Deepwater Horizon oil rig, had pledged to take "full responsibility" and said it would pay for "legitimate claims" stemming from the disaster.

So far, the company has been striving to shut off the flow of oil from the well on three fronts, but all with little success.

Six underwater submarines are trying to activate a 450-ton blowout preventer that could turn off the supply.

The BP has also started drilling a relief well to divert the flow of oil, which could take up to three months to complete.

The construction of a giant dome containment structure, expected to cover the leaks and contain the spill, has also started.

However, this could take a month to finish and has never been tried before at such depths of water.

About 600 U.S. National Guard soldiers currently are on duty to help contain the spill, with another 1,000 on standby.