"This will be contained," the President pledged after a cabinet meeting focusing on the oil disaster.
Three days after his latest visit to the Gulf, the president insisted BP pay victims in full and without delay.
"I do not want to see BP nickel and dimming these businesses," he warned.
The Coast Guard disaster commander, Admiral Thad Allen, was at the White House for the meeting.
He says it's his people, not BP's, who are measuring the rate of the leak.
Allen added the government can't trust the company when billions of dollar in penalties are at stake.
"The amount of oil that leaks will help determine the fine that BP incurs," White House Press Secretary Robert Gibbs explained. "So, while our interests align on capping this well, we would never ask BP to tell us how much oil they think has leaked."
Admiral Allen also said ocean skimming will last into the fall, but marsh cleanup will take years.
As bad as the Exxon Valdez spill was in 1989, this is worse, not just bigger, but broken into patches.
Some of those are submerged.
The Obama message: "Don't despair."