If the drill mud can plug the leaking well, engineers will then cap it with cement.
Meanwhile, another huge underwater plume has been found south of Mobile, Alabama. Marine scientists say it may be 20 miles long and several miles wide.
Fishermen in the region are apparently getting sick because of the tainted waters. At least seven fishermen working to clean the spill for BP were hospitalized Wednesday and dozens of others have complained of similar symptoms after inhaling the noxious fumes: nausea, headaches, and dizziness.
"I'm mad as hell. I want everyone to know that. If they [the federal government] want a bigger role they can do that," fisherman AC Cooper told ABC News.
Some locals have blamed the Obama administration for responding too slowly, and putting its boot on BP's neck too late in the game.
"I think President Obama is going to have to take control of this situation and let the federal government take over the clean-up and let BP and their 'expertise' to do the blowout," said Clint Guidry, director of the Louisiana Shrimpers Association.
Allen said the government hired local fishermen to help with the cleanup and also to provide them with job opportunities. He said toxicologists are looking at what might be behind the fishermen's sickness, including food sources. But environmentalists say more needs to be done in ensuring the health of local fishermen.
"We as the public have a right to know and fisherman need to not have to chose between putting a meal on the table and their own health," said Miriam Rotkin-Ellman of the environmental group Natural Resources Defense Council. "Some of the fisherman have come to work with their own protection and told they are not allowed to wear it on the job."
Obama will visit the Gulf coast today, his second trip to the region since the leak began last month. White House officials say the purpose of his trip is to hear from local officials and other individuals at the scene and see what ideas they have about containing the oil spill.
The president is also visiting the region in the hopes of convincing locals that he is on the case and that the federal government is doing everything it can to contain the disaster.
The president held a nearly hour-long news conference Thursday to announce that planned oil exploration in the Gulf coast and off the Atlantic Coast will be cancelled and a six-month moratorium will be placed on new, deepwater drilling permits.
The president also pushed back against critics who say the federal government didn't act quickly enough.
"Those who think that we were either slow on our response or lacked urgency don't know the facts," Obama said. "This has been our highest priority since this crisis occurred."
At the same time, he also took responsibility, saying the federal government is in charge of containing the oil spill, not BP.
"I take responsibility," he said."It is my job to make sure that everything is done to shut this down."
A USA Today/Gallup poll released Thursday showed that 6 in 10 Americans say the government is doing a "poor" job on the oil spill.
Democratic lawmakers from the region say too little is being done to contain the worst ecological disaster caused by an oil spill in U.S. history.
"Everything that I know and love is at risk," an emotional Rep. Charlie Melancon, D-La., said Thursday. "Even though this marsh lies along coastal Louisiana, these are America's wetlands."
Plaquemines Parish president Billy Nungesser has been a vocal critic of the federal government's response to the oil disaster, even calling Allen a "national embarrassment."
"I want him [Obama] to say that they're doing everything physically possible to keep this oil from destroying our wetlands," Nungesser, who is based in Venice, Louisiana, said on "GMA" today. "That's all we've been asking for from the beginning.
"I don't think the president knew what was really going on."
ABC News' Jake Tapper and Karen Travers contributed to this report.