Grace Wyler/Business Insider
Several influential groups exert pressure on members of congress by telling them that they'll be graded at the end of their term based on how they vote.
The interest groups pick several votes they deem crucial and use them to figure out who is most in line with their vision.
Some of the most crucial scores come from two major conservative groups — the Club for Growth and the American Conservative Union — and one major publication, The National Journal.
Members often use these scores as feathers in their cap, scoring bragging rights as the most conservative members of their caucus.
We averaged these three metrics to figure out the most conservative members of the U.S.