Which job should I take, and why?

I am a two year high school teacher. I have been approached by a state agency to work for them with the potential in one year to be promoted to a director postion making 80,000 + However my first year in the agency will pay a little less than what I will be making as a teacher. I am currently working on my master's degree, and I wil be done in a semester. Should I stay a teacher with the potential of being a principal, or should I go to the state agency with the potential of being the director?