A brewer's decision to stop a pub selling a locally-produced beer has led to a petition being organised in Lewes and a public meeting.
Campaigners said most drinks sold in the pub are made by Harveys
Pub group and brewer Greene King owns the Lewes Arms in the East Sussex town.
The Suffolk-based firm said it would stop serving Harveys beer, which is made in Lewes, at Christmas, replacing it with its own beer.
Greene King said it was committed to ensuring its pubs had a range of ales. Regulars said they would go elsewhere.
John May, a campaigner and a regular at the pub, said: "About 80% of the drink sold in the Lewes Arms probably is Harveys.
"The majority of people will go elsewhere and the pub will lose its community, which is in this day and age is very important."
Greene King operations director Kris Gumbrell said: "We are committed to all our pubs having a great range of cask ales, and of course you'd expect us to want to serve our own award-winning quality ales in our own pubs.
"We are very proud of our premium beers and we are confident that our fine selection of ales and our plans for further investment in the pub will enable our customers to continue to enjoy the warm welcome offered by the Lewes Arms."
Miles Jenner, managing director of Harveys Brewery, said: "Greene King have owned the freehold of the pub for the past 10 years and can stipulate what beers they wish to sell there.
"While their Bury St Edmunds ales are extremely good, it appears that customers at Lewes Arms prefer to drink local beers which we have produced in Lewes.
"We are very touched by their loyalty."