Asenator, who has won two consecutive congressional elections a few years ago, is planning to run for a third term. in this scenario, it can be said that the senator is a(n)

in this scenario, it can be said that the senator is an incumbent
In political term, incumbent means someone that currently hold a specific position. Until a replacement won the votes, the current senator still has the right to use all the right of a senator even during the election process