My boss is threatening to demote me for supposedly bad performance, what are my rights and options to avoid this?

Question Details:

About a month ago my boss "counseled" me. I'm a department lead for a national office supply chain; their copy center to be precise. I was informed that based on my recent performance he had the right/ability to fire me. He said he didn't want to, but that I would probably be looking at a demotion in a best case scenario. Yesterday I found out that he is indeed planning on demoting both me and 1 other employee. Both of our performances have been fine, and since the talk last month my performance and "dollars" coming in have been some of the highest in the company. What do I do now? Important Notice