The vote to fill an empty seat must be on the meeting's agenda. The procedure of appointing directors to fill the casual vacancy.This article details how vacancies are filled when they occur in the United States Senate. The same is true of vacancies on a fire board that has to fill vacancies within 90 days or the responsibility falls to the board of supervisors. United States Senator1. • Governor appoints person of same political party to fill the vacancy. Research the Board or Commission you are interested in serving on, using the links below. Payable to "Arizona Corporation. Commission," with all words spelled out and no abbreviations. United States Senator1.