of mexico until a pair of relief wells are completed in august at the earliest. today, president obama s energy adviser said she is now prepared for the worst and called this probably the biggest environmental disaster in american history. we have three reporters on this story tonight, and we re going to start with abc s matt gutman, in buras, louisiana. reporter: good evening, dan. and that next plan, which is basically another containment system, could start as early as monday. if it fails, and there is a significant chance it might, bp officials say they have a couple of tricks left in their arsenal, but each one of them is riskier than the other. they re running out of letters. this is plan g. we failed to wrestle the beast to the ground yesterday. we re going to put a cap on it. reporter: that beast is the well, and bp has given up on killing. now, they can only hope to capture the oil while they drill the relief wells, which they say will finally fix this. the new