I have been offered a US government job that is on the General Schedule pay system. This is the 3rd time they have tried to fill the position (I didn't apply the other times). The position requires a PhD, clinical experience, and research experience in a very narrowly defined sub field. I am friendly with one of the members of the interview panel and he unofficially said that only a few applicants made it through the HR screen and the panel were not happy with anyone else besides me.
What aspects of the job offer can I negotiate? The job was advertised at a single grade, so I do not believe that the grade can be negotiated. I think I can negotiate the starting step within the grade. I believe of the recruitment, relocation, and retention incentives I can only ask for a recruitment incentive since I am not currently a government employee. My friend on the interview panel said I can negotiate vacation time up from 13 days to 20 days, but I cannot find the policy on this. What else can be negotiated?