past their own 48-hour deadline? >> reporter: well, because they know this is so crucial. they want to make sure everything is going to be in tiptop shape before they go to the next step. and they will start pumping the oil back up to the surface, and they are making sure things are fine. the psi numbers, they wanted them to go up. they have not reached the level scientists were anticipating. the opposite, moving down, would indicate there is some kind of issue, leaking someplace, and even, heaven's forbid, a rupture on the ocean floor. if they do take that procedure, there will be some oil back into the gulf of mexico that will come from the valves. but even that, it will be temporary as they bring the oil to the surface. and the thing is really going to