Twenty-four hours after confirming that the Deepwater Horizon disaster was the worst oil spill in history, the US government is now reporting that most of the crude that was spilled has already disappeared from the Gulf waters.
The two statements are not incompatible, but it is clear that there has been a huge and decisive shift in how the story is being presented to the US public.
Suddenly the view from the Gulf shore is clearer and brighter. For the White House, this is a priceless political opportunity.
For months, the science looked bleak and the administration's only tactic was to hold BP's feet to the fire in the hope that the American people would blame the oil company rather than US President Barack Obama.
It worked well enough but it still made the White House look weak. It could not clean up the oil itself and it did not seem to be having much luck in forcing BP to do it either.
And the real problem was that it took control of the national news agenda out of the hands of the White House and left it adrift on the winds and waves of the Gulf of Mexico.
Mr Obama and his advisers would have preferred to spend the summer rolling out a couple of landmark accomplishments to focus the minds of voters ahead of autumn campaigning for the mid-term elections in early November.
There was the financial reform bill of course - a response to the unpopular bail-out of the banking system which Mr Obama inherited from ex-President George W Bush. He would have liked to sell that legislation to American voters as a populist package reining in the greedy and incompetent Titans of Wall Street who triggered the financial meltdown.
And there was this week's announcement that the winding-down of combat operations in Iraq is on schedule.
Those stories were duly reported, but ever since the blow-out at Deepwater Horizon, everything that has happened in the US has been shrouded in a blanket of oil.
It is the kind of period which makes you wonder if it has not become almost impossible to be president in the modern America of instant, constant news.
'Beginning of the end'
One of the things that Americans liked about Mr Obama as a candidate was his calm, even cerebral demeanour. Now he is the president, they want to see him playing Whack-a-Mole with every crisis that comes up - offering a quote here, an interview there and an on-site visit wherever it hurts.
Modern presidents end up reacting to events much more than they dictate them, however slick and thoughtful their press people might be.
No wonder the White House, desperate to sell what it sees as Mr Obama's achievements over the next couple of months, seized on the startling positive news its scientific researchers have just come up with.
You will still see plenty of news about the Gulf, but now that the White House has cast this as the "beginning of the end", the feel of the story is likely to change.
It might even sink to the bottom of the news agenda, as hard to find as the microscopic globules of dispersed crude which must surely still be out there somewhere.
Admiral Thad Allen, America's go-to guy on marine disaster, may be going on that famously delayed holiday with his wife sooner than he thought.
But rolling news, like gushing oil, can be difficult to handle - and there are choppy waters to come where the White House might find itself embroiled again.
Future drilling uncertain
First is the question of what attitude to strike towards BP - now that Mr Obama has stopped referring to it pointedly and incorrectly as "British Petroleum". True, it did spill the oil in the first place, but then on the other hand it has now plugged the leak and fixed at least some of the damage.
BP had to set aside a whopping $20bn (£12.6bn) for future claims of liability and loss of income among fishermen and the like.
If the final bill is less than that, might BP get some of its money back? After all, it is a huge employer in both Britain and the US, and its shares are widely held on both sides of the Atlantic.
Both the UK and US need a viable BP, but there will be fury in some states on the Gulf of Mexico if it appears that official anger towards the company is being ratcheted down.
Then there is the question of what happens if the science comes back to bite the White House. It will be tough for the administration to find the right note if the dispersed oil or the chemical used to disperse it turn out to be more damaging than seems likely right now.
And finally there is the tough question about how to handle deepwater drilling in the future.
Plenty of people in the oil industry down on the Gulf Coast believe the Obama administration listens too much to environmentalists and not enough to them. They believe the president seized on this accident to move against deepwater drilling, and they fear that some rigs might start to leave the Gulf of Mexico to look for work elsewhere in the world.
Banning deepwater drilling might please the environmental left of the Democratic Party, but it will worry lots of Americans who do not like to see anything that might increase their strategic dependence on foreign oil. Coming up with a convincing middle way on that issue remains a daunting challenge.
Still, for now, things look better in the Gulf than they have done for months. The oil has stopped flowing and the water is already cleaner than anyone had thought possible.
Mr Obama's people have struggled to cap the news just as BP has struggled to cap the well, and they will be relieved today that even if they have not quite reached the end of this story, they have at least reached the beginning of the end.