They just have to keep pissing off ever greater numbers of people (as they have been doing). As long as they can control how many people know the truth about what they are doing (and the disasterous consequences), they can continue to mislead large numbers of people. A disaster like Katrina, that affects so many thousands of people, makes it awful hard for them to cover up the truth. When the number of people who know the truth reaches critical mass... watch out, Karl Rove.