Incumbents are the current officeholders who are seeking reelection. They already hold the position they are running for and have an advantage over challengers.
Related terms
Gerrymandering: The manipulation of electoral district boundaries to give an unfair advantage to a particular political party or group.
Name recognition: The level of familiarity voters have with a candidate's name, usually gained through previous campaigns or media exposure.
Campaign finance: The funding of election campaigns, which can heavily influence an incumbent's ability to run a successful campaign.