Incumbent
（重定向自Incumbent advantage）
The incumbent is the current holder of a political office. This term is usually used in reference to elections, in which races can often be defined as being between an incumbent and non-incumbent(s). For example, in the 2012 United States presidential election, Barack Obama was the incumbent, because he had been the president in the previous term while the election sought to determine the president for the current term. A race without an incumbent is referred to as an open seat.