NEW ORLEANS -- BP said Monday it hopes to siphon as much as half of the oil leaking into the Gulf of Mexico and is getting ready to shoot mud into a blown-out well later this week to try and stop all of it.

Meanwhile, scientists said they were concerned about the ooze reaching a major ocean current that could carry it through the Florida Keys.

BP PLC chief operating officer Doug Suttles said at a news conference that the company never again will try to produce oil from the well, though BP did not rule out drilling elsewhere in the reservoir. "The right thing to do is permanently plug this well, and that's what we will do," Suttles said.

BP's mile-long tube is funneling a little more than 42,000 gallons of crude a day from the well into a tanker ship.

That would be about one-fifth of the 210,000 gallons the company and the U.S. Coast Guard have estimated are gushing out each day, though scientists who have studied video of the leak say it could be much bigger.

Suttles said BP would be pleased if the siphoning eventually captures half of the oil, though the company originally said it hoped the tube would catch most of it. Chemicals also were being used to disperse the oil underwater.

The political fallout from the spill continues. Congress is holding hearings, and the federal Minerals Management Service said Monday that Chris Oynes, who oversees offshore drilling programs, will retire at the end of the month.

Oynes has come under criticism for being too close to the industry the agency oversees.

Millions of gallons of oil already have gushed into the Gulf, and researchers said that in recent days they have discovered miles-long underwater plumes of oil that could poison and suffocate sea life across the food chain, with damage that could endure for a decade or more.

The National Oceanic and Atmospheric Administration said Monday that the researchers' announcement of the oil plumes was premature, and that further tests need to be conducted to confirm that the plumes detected were indeed caused by the well blowout.

The company said Monday that it has started drilling a second well to relieve pressure on the blown-out well and also getting ready to try a procedure known as a top-kill that uses a tube to shoot mud and concrete directly into a device on the well called the blowout preventer to stop the oil.

As engineers worked to get a better handle on the spill, a researcher told The Associated Press that computer models show the oil may already have seeped into a powerful water stream known as the loop current, which could propel it into the Atlantic Ocean.

The U.S. Coast Guard said 20 tar balls have been found off Key West, Fla., but the agency stopped short of saying whether they came from a massive oil spill in the Gulf of Mexico.

The Coast Guard says the Florida Park Service found the tar balls on Monday during a shoreline survey. The balls were 3 to 8 inches in diameter.