Is an organization that seeks to attain political power within a government, usually by participating in electoral campaigns. Parties often espouse a certain ideology, but may also represent a coalition among disparate interests. In parliamentary systems of government, most political parties have an elected leader who, if his or her party is elected by absolute majority, or with a relative majority within the coalition where tradition is thus, becomes head of government. In presidential systems, the President may be elected as a representative of his party; however, in many nations he is forced to relinquish his connections with his party upon the assumption of office as head of state.
In certain electoral situations a coalition government may be formed from members of more than one party. This is more common after elections using proportional representation rather than a "first past the post" system. Partisanship is the tendency of supporters of political parties to subscribe to or at least support their party's views and policies in contrast to those of other parties. Differentiation is essential to most political parties: they must be different at least in some ways to other parties to compete in politics and win elections. Extreme partisanship is sometimes referred to as partisan warfare.