A Question about the Secretary of State

Is there some reason Bill Clinton can't be made secretary of state? I like Hillary in the senate, and honestly, I think Bill would be a better SoS. But maybe there is some technicality about that, like is SoS in the line of succession?

A political clairification

From my last post, it might be assumed that I am a Clinton fan. I am not. I'd like to see them exit the stage post haste. Hillary in the senate is okay, because I think she'll do a good job pushing universal health care along.

But if we must have a Clinton in the cabinet, I'd rather have Bill than Hillary. Hence my question (thanks for all the replies, people!).

If I had to pick an SoS, I'd pick Gov. Bill Richardson or my favorite politician, Gov. Brian Schweitzer (he speaks fluent Arabic! but his big flaw is that he is really attached to oil extraction from coal, which doesn't seem like a good idea at all to me). Or promote a long time professional in the Foreign Service, how novel would that be.