One way that opposition to the Civil War was suppressed was the denial of what right?
and
What is set up to make political contributions to candidates for elected office?
Your answer could be states rights. Check this site for more information.
http://www.answers.com/topic/origins-of-the-american-civil-war
This site has the answer to your second question.
http://en.wikipedia.org/wiki/Political_action_committee