Most approaches to managing change ignore or trivialize the need to build commitment to changes such as mergers, reengineering, and new software systems such as ERPs. We live in an age of rapid and chaotic change. Failed changes cost organizations dearly. Research indicates that resistance is the main reason why so many new initiatives go way over budget or get implemented in ways that really weren't worth all the effort and cost. You must know your organization's capacity to handle major changes.
All major changes demand the active support of many individuals and groups.
Without the commitment of these critical people, the change is put at serious risk. In many cases you must build bridges with these people. In other instances, you need to repair damaged bridges. And, in all cases, you need to keep good bridges in working order. How you handled change in the past is the best indicator of how you'll handle it today.