In the past, I have negotiated salaries based on what the employee is worth in the area where they are employed. It would be hard for them to argue that you are

In the past, I have negotiated salaries based on what the employee is worth in the area where they are employed. It would be hard for them to argue that you are not in NYC and you don't deserve a competative DC salary. If they want you then they need to offer competative rates that make it easy to decide to join them. If they can't do that then jog on. As senior talent, the job market is currently in your favor.