Updated at 6:53 p.m. EDT
Newly-released internal documents show BP PLC estimated 4.2 million gallons of oil a day could gush from a damaged well in the Gulf of Mexico if all equipment restricting the flow was removed and company models were wrong.
The estimates have changed drastically since the Deepwater Horizon sank, from 1,000 barrels a day to 5,000. Then 12,000 to 19,000. Then 20,000 to 40,000. Now 35,000 to 60,000 barrels, reports CBS News correspondent Don Teague.
Rep. Ed Markey, D-Mass., released the documents Sunday showing BP said in a worst-case scenario the leak could gush between 2.3 million and 4.2 million gallons of oil per day. That's as much as 100,000 barrels of oil a day.
The current worst-case estimate of what's leaking is 2.5 million gallons a day.
Special Section: Disaster in the Gulf
The documents anticipate a scenario where the blowout preventer and other equipment on the sea floor were removed, which was never done.
BP spokesman Tony Odone said the documents were submitted to Congress before BP America President Lamar McKay testified in early May.
Judge to Hear Bid to Overturn Halt on Drilling
Several oil service companies are asking a federal judge to block the Interior Department from enforcing a six-month moratorium on new deepwater drilling projects in the Gulf of Mexico.
U.S. District Judge Martin Feldman is scheduled to hear arguments Monday on Hornbeck Offshore Services' bid for a court-ordered lifting of the moratorium.
A lawsuit filed by the Covington, La.-based company claims the government arbitrarily imposed the moratorium and suspended drilling at 33 existing exploratory wells without any proof that the operations posed a threat.
Hornbeck said the moratorium could cost Louisiana thousands of jobs and millions of dollars in lost wages.
Government lawyers said the company is making "alarmist and speculative" allegations about the potential economic impact of the move.
Republican lawmakers expressed support for at least a partial lifting of the moratorium, suggesting that if energy companies are not allowed to drill in American waters they will take their oil rigs to others' shores.
"We have hundreds if not thousands of wells in the Gulf of Mexico, and we're probably going to need more and more," said Sen. Richard Shelby, R-Ala., on CBS' "Face the Nation" Sunday. "If we don't [lift the moratorium], the oil drilling will go [overseas] and maybe not come back for a long time."
On the same program, Louisiana Republican Joseph Cao called for partial drilling, which he said would help ease the economic struggles the moratorium is causing for Gulf residents employed by the oil industry. Cao said oil rigs could continue working to drill until just before they would strike oil, so that the wells could be quickly completely once the moratorium is ended.
"We can allow them to dig up to the first 12, 13-thousand feet and then ask them to stop, and they have the technology to do that," he said.
Crews Drill Deep Into Gulf of Mexico to Halt Leak
Drilling crews are grinding ever deeper to build the relief wells that are the best hope of stopping the massive oil leak at the bottom of the Gulf of Mexico.
The crew of Transocean Ltd.'s Development Driller II was on track to pour cement starting early Sunday to firm up a section of metal casing lining one of two relief wells.
BP and government officials say the wells are the best option for cutting off the gusher that has spilled as much as 125 million gallons into the Gulf since the Transocean drilling rig Deepwater Horizon exploded April 20, killing 11 workers.
Back on land, coastal residents were infuriated by news that BP PLC CEO Tony Hayward was taking a break from overseeing efforts to stop the leak to watch his 52-foot yacht, "Bob," compete in a race around the Isle of Wight off southern England.
"Man, that ain't right. None of us can even go out fishing, and he's at the yacht races," said Bobby Pitre, 33, who runs a tattoo shop in Larose, La. "I wish we could get a day off from the oil, too."
BP spokespeople rushed to defend Hayward, who has drawn biting criticism as the public face of BP's halting efforts to stop the spill. BP is responsible for the cleanup because it was leasing the rig when it blew up.
"He's spending a few hours with his family at a weekend," said BP spokesman Robert Wine. "I'm sure that everyone would understand that."
The PR gaffe - yet another in a series by Hayward and the company - ended what could have been a good week for BP. About 50 miles off Louisiana's coast, a newly expanded containment system is capturing or incinerating more than 1 million gallons of oil daily, the first time it has approached its peak capacity, according to the Coast Guard.
BP hopes that by late June it will keep nearly 90 percent of the flow from the broken pipe from hitting the ocean.
It will likely be August before crews finish drilling the relief wells.
On the Development Driller II, one of two rigs working on the effort, BP wellsite leader Mickey Fruge said the well has reached a depth of roughly 5,000 feet below the seafloor. There's still another 8,000 feet to go.
The other well is deeper, but drilling superintendent Wendell Guidry says it's anyone's guess which team will intersect the damaged well first.
"The main thing is, you know, we try to keep the guys focused," Guidry said. "We're just treating this like we treat any other well that we drill."
Once a relief well intersects with the damaged well, BP plans to shoot heavy drilling mud down the well bore, then plug it with cement.
Meanwhile, Democratic Sens. Barbara Boxer of California and Bill Nelson of Florida said on CBS's "Face the Nation" Sunday that they have asked President Barack Obama to give the Navy a bigger role in the efforts to clean up the spill, which are now being overseen by the Coast Guard.
But asked on "Fox News Sunday" if the Pentagon could be doing more to help stop the leak or keep oil from washing up on shore, Defense Secretary Robert Gates said no.
"We have offered whatever capabilities we have," he said. "We don't have the kinds of equipment or particular expertise."
© 2010 CBS Interactive Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.