Answer:
Incumbency is the most important factor in congressional elections because people can look back on what you have done and use this to judge whether you would be good for a second term.
Step-by-step explanation:
An incumbent is someone who has already run a term in office. Incumbents use their policies to convince their constituents and others to vote for them. If there policies match up with their constituents/the majority they can get an extra term in office. If their policies don't match their constituents/the majority, they are likely not to get an extra term in office.