The Politics of Mexico take place in a framework of a federal presidential representative democratic republic whose government is based on a congressional system, whereby the president of Mexico is both head of state and head of government, and of a multi-party system. The federal government represents the United Mexican States and is divided into three branches: executive, legislative and judicial, as established by the Political Constitution of the United Mexican States, published in 1917. The constituent states of the federation must also have a republican form of government based on a congressional system as established by their respective constitutions.