This follows an announcement that the Department of Business, Energy and Industrial Strategy has agreed to launch an industry call for evidence of unfair trading practices, alongside the statutory review of the GCA role.
The GCA came into force in June 2013 with a remit to enforce the Grocery Supply Code of Practice (GSCOP) covering just the 10 biggest UK retailers.
But a NFU/BPOA code of good trading practice launched in 2013 failed to get any supermarkets to sign up.
Business minister Margot James is reviewing the code.
"While having a positive impact on the relationship between producers and suppliers, there has been lots of discussion about what more the GCA can do to support our farmers who are so often at the end of the chain and want more support in their negotiations with supermarkets and other companies.
"Through this consultation, all those that want to see the GCA's role extended have the chance to make their case and provide their evidence. I encourage farmers to have their say."