BP's latest experimental bid to plug its seabed oil gusher in the Gulf of Mexico hung in the balance early Wednesday as its top executive reviewed overnight tests before deciding whether to go ahead.
Chief Executive Tony Hayward said on NBC's "Today" show he would decide Wednesday morning whether to give the green light for crews to try to choke off the massive leak a mile below the sea by force-feeding it heavy drilling mud and cement. The spill started with an April 20 explosion and fire that sank the oil rig Deepwater Horizon and killed 11 workers.
Testimony ahead of a hearing Tuesday and BP's own internal investigation showed there were warning signs of problems before the blast. One rig worker said managers from rig owner Transocean Ltd. worried that day that BP, which ran the operation, as not taking the right steps to contain the pressure.
Senior Transocean managers complained April 20 that BP was "taking shortcuts" by replacing heavy drilling fluid with seawater in the well, according to sworn testimony by Truitt Crawford, a rig roustabout. BP was leasing the rig and is responsible for stopping the leak and the cleanup.
The seawater was being used in preparation for dropping a final blob of cement into the well as a temporary plug for the pipe. Workers had finished pumping the cement into the exploratory well to bolster and seal it against leaks until a later production phase.
Crawford said seawater would provide less weight to contain surging pressure from the ocean depths. His testimony was expected to be part of a hearing in New Orleans. A BP spokesman declined to comment on what he said.
Dozens of worker statements obtained by The Associated Press describe the hours and minutes before the sudden, violent blowout and many said they were concerned about the pressure coming from below.
And tests within an hour of the blast indicted the pressure was building, according to a congressional memo about new warning signs that a BP investigation indicated. The buildup was an "indicator of a very large abnormality," in the well, BP's investigator indicated.
Still, the rig team was "satisfied" that another test was successful and resumed adding the seawater, said the memo by U.S. Reps. Henry Waxman and Bart Stupak to members of the Committee on Energy and Commerce, which is investigating what went wrong.
There were other warning signs of problems included an unexpected loss of fluid from a pipe known as a riser five hours before the explosion, which could have indicated a leak in the blowout preventer, the memo said. The blowout preventer is designed to shut down the well in case of an emergency. BP has cited its failure as a contributor to the blast.
Plugging the leak was the focus Wednesday 50 miles off the Louisiana coast.
Hayward told NBC's "Today" show that if he gives the green light, he expected the top kill procedure to happen Wednesday.
The top kill involves pumping enough mud into the gusher to overcome the flow of the well, which has leaked millions of gallons of oil into the water since an April 20 rig explosion. Engineers then plan to follow it up with cement that the company hopes will permanently seal the well.
"I have to say that it will be a day or two before we can have certainty that it's worked." Hayward said on NBC. He said pressure tests ahead of the procedure continued through the night and he would review the results before deciding whether to go ahead.
The top kill has been successful in aboveground wells but has never been tried a mile beneath the sea. Hayward earlier pegged its chances of success in this case at 60 percent to 70 percent.
It is the company's latest effort to stem the spill and comes as politicians and Gulf residents are losing patience with the company over several failed attempts to stop the leak.
At least 7 million gallons of crude have spilled into the sea, fouling Louisiana's marshes, coating birds and other wildlife and threatening livelihoods from fishing and tourism.
BP said those who want can watch the procedure online. Live video of the leak has been available for the past few days, and BP said that it will continue throughout the procedure.
If all goes as planned, engineers will pump fluid twice as dense as water from two barges into two 3-inch-wide lines that will feed it into the blowout preventer. Crews plan to pump it in at a rate of 1,680 to 2,100 gallons per minute in hopes of counteracting the upward pressure of the oil gushing to the surface. They stockpiled some 50,000 barrels of the heavy mud, a manufactured substance that resembles clay.
Bob Bea, an engineering professor at the University of California at Berkeley, said the procedure carries a high risk of failure because of the velocity at which the oil may be spewing.
"I certainly pray that it works, because if it doesn't there's this long waiting time" before BP can dig relief wells that would cut off the flow, Bea told the AP.
Wells said it could take anywhere from a few hours to two days to determine whether the top kill is working.
President Barack Obama could get the results in person. He prepared to head to the Gulf on Friday to review efforts to halt the contaminating crude that scientists said seems to be growing significantly darker, from what they can see in the underwater video. It suggests that heavier, more-polluting oil is spewing out.
Ahead of his trip, Obama planned to address an Interior Department review of offshore drilling that's expected to recommend tougher safety protocols and inspections for the industry, according to an administration official. The official spoke on condition of anonymity ahead of the public release Thursday of the findings of the 30-day review Obama ordered after the spill.
A new report from the Interior Department's acting inspector general alleged that drilling regulators have been so close to oil and gas companies they've been accepting gifts including hunting and fishing trips and even negotiating to go work for them.
The Interior Department's acting inspector general, Mary Kendall, said her report began as a routine investigation.
"Unfortunately, given the events of April 20 of this year, this report had become anything but routine, and I feel compelled to release it now," she said.
Her biggest concern is the ease with which minerals agency employees move between industry and government, Kendall said. While no specifics were included in the report, "we discovered that the individuals involved in the fraternizing and gift exchange -- both government and industry -- have often known one another since childhood," Kendall said.
Associated Press writers Mike Kunzelman in New Orleans, Jeff Donn in Boston, Ben Evans, Ben Feller, Fred Frommer and Erica Werner in Washington, and Holbrook Mohr in Jackson, Miss., contributed to this story.