There are 12 known factors that can negatively impact your project delivery. Even one of these factors can cause project delays and cost increases. The interaction of several of these factors can mean the collapse of a project.
As a good project manager, you never play the blame game, but signal to your management that you take responsibility and are solution focused. Quick and thoughtful project decisions lead to a rapid re-establishment of trust in your project and everyone's belief in the joint success of the project.