Sometimes, cherished positions are challenged. Face it, the people who get covers on national news magazines are either saints, politicians, billionaires, or axe murderers. On the other hand, products and services don't sell until people know about them. Work with an experienced PR person to develop realistic goals based on reasonable expectations for your situation. Then periodically measure progress against your goals.
Professionals spend years perfecting a body of knowledge and a set of skills.
Treat this person as a insider, and give him or her all the information needed to do the job. The statement that if no one owns an activity, and if it isn't made important, it won't get done is a truism. But it's still true. A PR professional can't do it all alone. People in your organization will have to participate, to devote some time and energy in support of the effort.