Cities are managed by elected politicians and appointed officials or professionals. Often, there are basic contradictions between legitimate interests of the two groups. Because politicians are responsible to the electorate, they must have the means to carry out the policies they have promised to pursue. In particular, they must be able to hire and trust professionals who will implement there policies and to terminate them if need be. Professionals who work in municipal administration, on the other hand must enjoy a certain degree of independence as will as a large degree of tenure security. Otherwise, municipal administration will never be able to attract people with high caliber. There is no simple set of rules to solve this contradiction. More so the roles of professionals in city management vary from country to country.