When you want to defend or support someone or something, you might use the phrase "speak up for." However, there are plenty of other ways to express this idea, depending on the situation. For example, you could "advocate for," "champion," "promote," "stand up for," "back," "vouch for," "uphold," "endorse," "defend," or "support" someone or something. Each of these words has slightly different connotations, so consider which one best fits the specific context and tone you are aiming for. Using synonyms for "speak up for" can help you communicate your thoughts more effectively and capture the nuance of your intention.