Some 342 workers at Burton’s Foods have been told that they will be sacked and the Wirral factory closed.
The workers make Jammie Dodgers and Wagon Wheels.
Unite has now entered into a 90 day consultation period with management.
Ritchie James, Unite regional officer, said: “This plant was saved from the axe in 2007 through the efforts of the workers, their friends in the community and their union. There is a mountain to climb but we will be doing everything in our power to make sure the last campaign wasn’t for nothing.”