BP's so-called "top kill" operation to plug the oil leak in the Gulf of Mexico continues tonight, though the company has again paused the flow of mud to attempt a second "junk shot" in hopes of stopping up the blowout preventer on the ocean floor.
At a press conference this evening, BP executive Doug Suttles said the halt of the mud flow is not a sign that their efforts are not working.
"We've had periods of pumping followed by periods of monitoring," Suttles said. "I think the key element here is patience."
He said the top kill and junk shot operations will continue for 24 to 48 hours.
Watch 'ABC World News' tonight for more on the attempt to stop the BP oil spill.
Overnight, BP conducted its first junk shot, injecting tons of debris -- like golf balls and shredded tires -- into the pipes leaking oil. They then resumed pumping mud into the leaking well and were able to again stop the oil flow.
But BP doesn't have enough mud in the well to lower the pressure sufficiently to finish the job. Until they reach that point, they cannot inject cement into the well to cap it and declare it dead. It will be Sunday before they know whether the top kill worked and cement can be poured.
But for many in the region, BP is losing credibility faster than it's losing oil. Executives said they would know something in 12 hours, then 24, 48 and now 96 hours. People complain that for 16 hours yesterday, the company put the top kill procedure on pause and didn't bother to tell anyone all day.
Suttles, who flew over the region today, pointed to evidence on the water's surface as reason to hope, describing it as the "least amount of oil that I've seen offshore since my very first flight."
He cautioned against drawing conclusions from the live video feed of the wellhead 5,000 feet below surface.
"Watching the plume is not an indication of how the job is going," Suttles said.
On Board the Deepwater Enterprise
Seventy miles from the Louisiana shore, an armada of 50 ships surrounds the site of the leaking well, where the Deepwater Horizon rig exploded and sank in the gulf 39 days ago. On those ships, BP employees are working desperately to plug the leak.
The Deepwater Enterprise is the lead ship in that armada, and ABC News' Jeffrey Kofman was invited on board today, the first journalist allowed to witness the ongoing operation.
For the first time since the rig explosion that started the leak, there is no oil slick around the site of the accident; engineers say the mud being pumped into the well has contained much of the oil.
Hayward: Pressure Has Increased in Blowout Preventer
Tony Hayward, the C.E.O. of BP who invited ABC News on board today, expressed cautious optimism that the top kill will work in the next 48 hours.
Hayward said that the pressure at the bottom of the blowout preventer had increased by some 300 psi, a positive sign that the leak may beginning to clog.
Hayward was not ready to call it a success, saying that the company had not yet put a bullet in the leak's head. He said that there's still a lot of work to be done, and if the top kill operation fails, the company has back-up plans in place designed to stop this leak.