The advantage combines resources and selection. Officeholders can communicate, claim credit, assist constituents, and raise money from established networks; strong candidates also tend to become incumbents in the first place. High reelection rates therefore do not measure the causal benefit of officeholding by themselves.

The effect varies with chamber and context. Senate races attract stronger challengers and statewide attention, while House districts often provide safer electoral bases. Redistricting can erase familiar constituencies, and scandal, primary conflict, or a national partisan wave can overwhelm the ordinary benefits of office.

Casework is electorally useful because a solved problem is visible to the recipient, but staff may not use public resources for campaign activity. Distinguish official service and name recognition from legal immunity: incumbency improves opportunities to compete; it does not guarantee renomination or reelection.

Video lesson: The Bicameral Congress: Crash Course Government and Politics #2