Caucusing

Caucusing is the practice where a portion of the membership of a voting body agrees to vote as a block, even though some members of the 'caucus' might be inclined to vote the other way.

The motivation for caucusing is that it allows members of the block disproportional influence in the outcome of the final vote. For example, suppose that one third of the members agree to always vote as a block. Once they decide how they vote, it will require only a sixth of the remaining voters to agree for the will of the caucus to prevail. That is, a narrow minority in the caucus will override anything less than five sixths of the remainder. As an extreme case, if only "fifty percent plus one" of the caucusing voters support a motion, and one sixth of the rest support the motion, it will succeed, even though almost two thirds of voters are opposed to the motion.

The motivation for agreeing to vote contrary to ones own natural inclination on an issue is the knowledge that one will enjoy the support of the caucus on other issues.