New Orleans, Louisiana (CNN) -- BP will try again within the next day to cap a well that has gushed millions of gallons of oil into the Gulf of Mexico, the energy company said Friday.





The latest attempt will involve inserting a tube into a ruptured pipe, collecting oil and sending it to a vessel on the surface, said Mark Proegler, a BP spokesman.





The insertion tube was on the sea floor, and engineers planned to move it into place later in the day, Proegler said.





The company has lowered a smaller containment dome for use if the insertion tube does not stem the flow of oil into the water, Proegler said.





But Adm. Thad Allen, commandant of the U.S. Coast Guard, said twice Friday that the containment dome, referred to as a "top hat," was the first choice, followed by the insertion tube.





Officials could not explain the discrepancy.





Neither procedure would be a permanent solution, Allen said Friday in Mississippi. The procedures, he said, "will reduce the leakage, not stop the leakage."





The ultimate solution, Allen said, will be achieved by relief wells that are being drilled near the leak site. Those will take weeks, if not months, to complete, BP has said.





After much discussion over whether the use of subsea dispersants could cause ecological damage, Coast Guard Rear Adm. Mary Landry said Friday that officials have concluded that it "is an option we can consider and will move ahead with."





The decision was made after the results of three tests were analyzed, she said. "This is not a decision that was made lightly, but it is a series of tradeoffs. You're really trying to minimize the impact on the environment as best as possible."





Doug Suttles, BP's chief operating officer for exploration and production, said the company has spent more than $450 million responding to the spill and that more than 14,000 people are involved in the effort.





To date, more than 1.2 million feet of boom have been deployed and another 400,000 feet of boom have been staged for deployment, he said. In all, the company is trying to accumulate 3.5 million feet of boom.





The forecast this weekend and early next week "looks very favorable to use all tools," he said, citing burning, skimming operations and use of surface and subsurface dispersants.





Suttles said the spill has had "limited impact" on shore, with oil being found in four locations in Louisiana, two in Alabama and one in Mississippi.





In Washington, President Barack Obama criticized executives from BP and two other companies for blaming each other for the catastrophe.





"It is absolutely essential that, going forward, we put in place every necessary safeguard and protection so that a tragedy like this oil spill does not happen again," Obama said after meeting Friday with Cabinet members to discuss the spill.





Read about oil spill responses





"This is a responsibility that all of us share," Obama said. "The oil companies share it. The manufacturers of this equipment share it. The agencies in the federal government in charge of oversight share that responsibility. I will not tolerate more finger-pointing or irresponsibility."





BP's efforts to plug the leak come amid growing concern that the company has been low-balling how much oil has poured out of the well.





Rep. Edward Markey, D-Massachusetts, sent BP a letter Friday asking for details from federal agencies about the methods they are using to analyze the oil leak.





Markey, who chairs a congressional subcommittee on energy and the environment, said he would launch a formal inquiry after learning of independent estimates that are significantly higher than the amount BP officials have provided.





"The public needs to know the answers to very basic questions: how much oil is leaking into the Gulf and how much oil can be expected to end up on our shores and our ocean environment?" Markey said in a letter to BP. "I am concerned that an underestimation of the flow may be impeding the ability to solve the leak and
How many feet of boom was deployed? where did this happen Who is critical of company executives for trying to shift blame to one another? How many people were involved in the clean-up? How many people are involved in clean-up and efforts? What was deployed to prevent oily water from reaching shore? Who was critical of company executives for trying to shift blame to one another?
more than 1.2 million Gulf of Mexico, President Barack Obama 14,000 14,000 more than 1.2 million feet of boom President Barack Obama
question: How many feet of boom was deployed?, answer: more than 1.2 million | question: where did this happen, answer: Gulf of Mexico, | question: Who is critical of company executives for trying to shift blame to one another?, answer: President Barack Obama | question: How many people were involved in the clean-up?, answer: 14,000 | question: How many people are involved in clean-up and efforts?, answer: 14,000 | question: What was deployed to prevent oily water from reaching shore?, answer: more than 1.2 million feet of boom | question: Who was critical of company executives for trying to shift blame to one another?, answer: President Barack Obama