Your goal here is to tip the balance away from suicide as a viable option. Allow the patient time to talk. Persons that are suicidal often feel that nobody understands or cares. They may be partially correct. Clinical depression is a difficult concept for the lay person to understand.
Depressed people are also difficult to be around on a daily basis.
These patients may be totally isolated because of their condition. By being available, listening, and showing concern you show that you do understand at that they are not totally alone. Assess motive for suicide. If you can help patient clarify their reasons for suicide it will score some points for you as a professional. It will also get your foot in the door and help you begin working towards some solutions.