The antonyms for the word "campaigned for" would be "opposed", "protested", or "resisted". These words suggest a level of opposition or disagreement with a particular stance or idea. While campaigning for something implies a level of support and advocating for a particular cause, opposing or protesting against something indicates a desire to challenge or change it. Resisting something suggests an active effort to prevent its success or implementation. By understanding these antonyms, we can better grasp the various perspectives and positions that may exist within a given issue or debate.