Incumbent congressmen have many advantages over their challengers.
So many that after two terms their reelection rate goes from an incredible 98.5 percent to an untouchable 100 percent. Perhaps the biggest advantage is their ability to use the power of the federal government for their friends and against their enemies. Recently Congressman Jay Dickey of Arkansas told a group of black farmers that he would not support a judgement in a lawsuit that the farmers had won against the Department of Agriculture. There you have it. The merits aren't the concern here, but rather, how effectively various interest groups can be bribed for their votes.