Principled politican compromising principles...?
You're going to have to explain that one to me.
Even the most principled politician sometimes needs to compromise on his/her principles if he/she wants to accomplish anything.
Example: The founders compromised in the US Constitution on the issue of slavery. They could not resolve the difference between the principles on which they sought to found the nation and the demands of some that slavery be maintained. So, they punted, leading to the greatest crisis America was to face.