Most of the people behind it are knee-jerk military-action-opposers. What they are doing is trying to threaten a greater proportion of the American public with conscription in the hopes that they will withdraw support for military action. In other words they want to scare people into coming around to their way of thinking - which is extortion.
What I still can't figure out is why the heck someone interviewing Rangel or Hagel doesn't just say "if you want a bigger military why doesn't Congress just increase the caps on military size and provide the funding to do it and let more volunteers enlist??" That would expose this whole issue as the fraudulent extortion attempt that it is.