Face the heat! Expressed in that way, it doesn't sound very attractive... but it's also what will lead to relief of tension. For when faced with news that is difficult to accept, co-workers need to express their anxieties and to ask their questions. Without this, by seeking to suppress "rebellion", we actually amplify it.       

Beating around the bush is human, but not very effective. It is better to announce the bad news in a single clear sentence, prepared in advance if possible. It should express the key information and underline - briefly! - how it is problematic for those concerned. Here again, do not try to avoid the problem for it will raise its head again later with even more force.       

He who speaks an unpopular message speaks of an obstacle to be overcome. It is thus necessary first to recognize the obstacle rather than to minimize it. Once this is done, you can then lead co-workers to see the situation from a more positive angle: What can this situation teach us? What might it lead us to change? Can we get something positive out of it?