with one voice
一口同聲地；一致通過

explanation : This idiom means that a number of different people or groups agree on a point or an issue.  It is often used in politics and business.  For example, a group of business men in one company might agree that everyone in their company has to convey the same message.

e.g. "We've had confusion in the past about our exchange policy, so it's important that every one speak with one voice on this issue."