Opinion Leaders are the ones that influence co-workers. They rally people, or divide them. They're found among the staff, not along lines of management. Their skeptical view of management is what makes staff listen to them. If you can win them over, staff will follow. Indeed, they may become your most steadfast supporters, and explain things to staff in ways that you or your leads cannot.
The lesser experienced project manager can easily alienate the opinion leaders. And it's understandable why. Often times, project managers are picked because they've proven themselves good business managers. Business managers have a longer relationship with staff and generally get the action they ask for with little debate. Project managers, on the other hand, are working with staff for the first time in many cases, and don't have the track record from which to expect unquestioned action. Further, project managers ask for actions that often break from traditional forms of communication, cross boundaries of authority, require frequent adjustments in priority, and generally can feel unfocused and misguided to staff.
At first it is a relief when you find most staff are willing to go with the flow, with little need for justification. Later however, you realize the resistant staff were the critical thinkers you really needed to ensure that the project's solutions are solid and will stand the test of time.
Early in the project you should discern which few of the project staff are likely to be resistant, and if brought on board, would bring others along. Take extra one-on-one time with these people. Keep an open mind in the discussions. If you are open to their criticisms, they will relax and gain a more balanced view of the project and your efforts. They will try to understand. Also, if you can strike a healthy discussion, they very likely will offer insights that will help you connect more effectively with project staff, and even improve the technical solution. To be clear, you are not seeking compliance from these individuals, you're seeking understanding and alignment. Their critical nature is often the very asset that keeps the project from making costly mistakes. Allow them to be critical, but provide a channel of two-way open communications to share thoughts and creative thinking. If these individuals are not directly reporting to you, create the same culture of exchange with your directs. In doing so, you are grooming them to be more effective project managers too.
Occasionally, skeptics enjoy the attention they get from their contrarian behavior more than the self-improvement and opportunity they get from higher level collaboration. These individuals are probably better served in a job outside of the project.
So it pays to take extra time with resistant staff, particularly early in a project as sentiments are being shaped, and explain the background and logic for your approach, in hopes that they will understand it, even improve on it, and in doing so influence others to follow.