Political patience wears thin as BP battles to contain leak

On the Gulf of Mexico: Political patience was whittling away for BP executives who can't stop a broken underwater well from pouring oil into the Gulf of Mexico where crews tried the latest solution — submerging a second containment box designed to funnel the gusher to a waiting tanker.

In back-to-back US Senate inquiries on Tuesday, lawmakers chastised officials from BP and its drilling partners over attempts to shift blame to each other.

They were asked to explain a "cascade of failures" that led to the catastrophic explosion on aboard a drilling rig and the blown-out wellhead that has spewed at least 4 million gallons of oil into the Gulf over three weeks.

"If this is like other catastrophic failures of technological systems in modern history, whether it was the sinking of the Titanic, Three Mile Island, or the loss of the Challenger, we will likely discover that there was a cascade of failures and technical and human and regulatory errors," said Senator Jeff Bingaman, chairman of the Energy and Natural Resources Committee.

Later Tuesday, a crane lifted the new box from the deck of the Viking Poseidon, one of the more than a dozen boats helping the containment effort, and lowered it into the sea about 80km off the Louisiana coast.

The first box sunk last week weighed 100 tonnes and company officials had hoped it could contain 85 per cent of the oil.

However, it was never tried at such depths — about a mile below the surface — and in chilly water. A slushy mixture of gas and water clogged the opening in the top of the peaked box and it was cast aside.

The latest box is much smaller — just two tonnes. It won't be placed over the spewing well right away because engineers want to make sure everything is configured correctly and avoid the same buildup, BP spokesman Bill Salvin said.

Crews also planned to pump in heated water and methanol so ice won't amass. It could be in place by Thursday.

Lawmakers' focus was on what failures may have led to the disaster. The corporate finger pointing prompted an admonishment from Republican Senator Lisa Murkowski of oil-rich Alaska that "we are all in this together" in trying to shut off the oil and find a safer way to exploit vital energy.