Dic: be in the balance, hang in the balance

• The fate of a project which could revolutionise the use of computers in hospitals hangs in the balance.
• He stood on the edge of the cliff, his life in the balance.
• With his fortune in the balance, John rolled the dice.

1. PHRASE : PHR after v, v-link PHR | If something hangs in the balance, it is uncertain whether it will happen or continue.
2. in the balance: in an undecided state; at risk. (Typically: be ~; hang ~.)

.... Cobuild, http://idioms.thefreedictionary.com/balance