The country has more than 40 active political parties. Together with several smaller parties, four political parties stand out: Workers' Party (PT), Brazilian Social Democracy Party (PSDB), Brazilian Democratic Movement (MDB) and Democrats (DEM). Fifteen political parties are represented in Congress. It is common for politicians to switch parties, and thus the proportion of congressional seats held by particular parties changes regularly. Almost all governmental and administrative functions are exercised by authorities and agencies affiliated to the Executive.