Saying "no" to a candidate who was referred
I work for a non-profit and am getting ready to bring a new hire on board for a position that's been open for almost a year (I've only been in my position 2 months). I'm concerned because a board member referred someone for the job and I interviewed him but am not offering him the position. I know it's the right decision; however, am somewhat nervous about alienating the volunteer who referred him. The volunteer is on our board, which supervises our CEO. He is also a very influential person in the community and I am depending on him to host our gala event this summer. I have only known him for 2 months, so I don't have a strong history/relationship that I can call on for his support of my decision.
Any suggestions on how to proceed? When do I tell him (the volunteer) in relation to when I notify the candidate? Do I give any reasons for my decision?
Thank you for any advice!