Incumbent members of Congress seldom get defeated.

From Bill Shipp's Georgia from InsiderAdvantage:

Incumbents seldom get defeated; since 1962, House incumbents nationwide have been re-elected an average of 93 percent of the time. The last time a Democratic congressman from Georgia was defeated for re-election in a general election was 11 years ago, when Buddy Darden and Don Johnson were tossed out by voters angry with those two because of their support of the Clinton Administration.