The power of incumbent is the name given to the advantage awarded to the those seeking reelection to an office they already hold.

The advantage exists for a number of reasons. Firstly, where a long term office holder is seeking reelection they are likely to have greater name recognition in the state/district so publicity is less of an issue than with a challenger.

Another factor, linked to greater name recognition is greater access to funds through sponsors and donors. Established candidates are likely to have a significant donor base either personally or through their political party making it easier to afford to run a campaign.

To highlight the success of the incumbency, reelection rates among those incumbents seeking reelection has been consistently over 80% for the last 50 years.