what is caucusing I have never heard of this and what does it have to do with the elections?

Answer 1

The term is frequently used to discuss the caucuses used by some states to select presidential nominees, such as the Iowa caucuses. Along these same lines, in early American history, the Congressional nominating caucus and legislative caucus were influential meetings of congressmen to decide the party's nominee for President and party platforms. Similar caucuses were held by the parties at state level.

Answer 2

http://en.wikipedia.org/wiki/Caucusing

This will tell you.
Basically it is bloc voting.