The brewery has warned unions that there will be job losses as it must make £1.5m of budget cuts.
Stephen Tompkins, a GMB union organiser, said "The Federation is an institution in the North East. It is one of the first things you see as you come into Tyneside on the A1. It is bad news and what the Federation stands for just makes it worse.
"When Vaux went, that was a massive blow and we have to hope the Federation isn't going the same way.
"The company is looking to build new markets and bring out new products, like alcopops and the new Angel Ale. Things have changed in the brewing industry and the Federation will have to change as well."
The company, which brews beers including Federation Ordinary, Fed Special, High Level Brown Ale, Pale Ale, LCL Premium Lager, Samson and Northumbrian Smooth, has been an official supplier to the House of Commons for 36 years.