"Unsure," "undecided," "uncertain," and "precarious" are all synonyms for the phrase "hang in the balance." Each of these expressions emphasize the precariousness of the situation or outcome, highlighting how the final result may tip one way or another. To "hover uncertainly" or "be in limbo" is also similar to the phrase, suggesting that there is no clear winner or decisive action being taken. "Tenuous," "unsettled," and "up in the air" are additional synonyms that denote instability or a lack of concrete resolution. Regardless of the specific word used, each synonym reflects the precariousness of a situation that has yet to be resolved.