"Up with" is a common phrase that means "in support of" or "in favor of". There are a number of synonyms that can be used to convey a similar meaning, such as "for", "in favor", and "in support of". Other options include "pro", "all for", and "behind". These synonyms can be used interchangeably in many situations, depending on the context and tone of the conversation. For example, someone might say "I'm all for raising the minimum wage" or "I'm behind the efforts to protect the environment". Overall, there are many ways to express support for an idea or cause without using the phrase "up with".