The firm which makes "one of the most iconic brands in the UK" has announced plans to cut almost half its workforce at a factory in a bid to ensure it can be stay there for "another 100 years".
Pladis, which makes Jacob's crackers, told about 760 workers at its site in Aintree, Liverpool, that it would cut jobs by next December.
The GMB union said up to 361 workers were facing redundancy.
The exact number of redundancies will be confirmed following a consultation.
The site, which was the first Jacob's factory in England, remains the primary producer of the brand's products, including Cream Crackers and Twiglets.
A Pladis representative said Jacob's was "one of the most iconic brands in the UK and has been around for over 100 years".
"To ensure it can remain for another 100 years, it is essential we address the current constraints we have at Aintree," they said.
They said the firm had proposed some changes, which included a "significant investment in the infrastructure", alongside a reduction in the site's "footprint".
"This proposal will now be subject to consultation with our employees, as it could result in a reduction in roles at Aintree from December 2024," they added.
GMB regional organiser Lisa Ryan said the announcement had left "many workers feeling frustrated and worried".
"Jacob's have sunk to new lows," she said.
"We will fight tooth and nail for the best outcome."
Members of the union took part in 11 weeks of industrial action at the site in 2022, before securing an increased pay deal from workers.