A PUB campaigner from Derbyshire said a debate in Parliament tomorrow could "make or break" the future of pubs.
MPs are due to discuss an amendment to the Government's Small Business, Enterprise and Employment Bill.
The amendment would allow landlords leasing pubs from large companies to have their rent independently reviewed to ensure it is fair.
It would also allow them to buy beer at competitive prices on the open market, which campaigners say would save about 60p a pint.
Critics say both moves would help to break the "beer tie" which they believe is killing the pub trade, resulting in the closure of thousands of pubs across the country.
Former GMB Union representative Dave Mountford, who runs the Boat Inn at Cromford, previously gave evidence in Parliament about the pressures landlords are placed under by pub companies.
He said the amendment "would be a game changer for the industry."
Mr Mountford, who has stepped into battles with previous pub companies, said: "This is now the result of eight years of campaigning. It's very important.
"If this amendment is passed, then once this law comes into effect, a tenant taking on a pub from a large or small pub company can say 'I don't want to be tied to your beers and prices, I want to be free of tie and pay a rent determined by the market'. It would be excellent.
"If this goes through then great, it will mean the industry will change and it would be fantastic.
"Tenants being able to buy their own beer would mean a great amount of freedom.
"If the amendment doesn't go through then there will be more closed pubs.
"It's all or nothing."
The Government is proposing to introduce a pubs code adjudicator to rule on disputes between landlords and large pub-owning companies.
Mr Mountford said: "The government is finally taking action to introduce a pubs watchdog in England and Wales. It's an amazing achievement.
"But still, too many communities are having to battle hard to save their local pubs from closing.
"Too many pubs are being lost forever due to unfair business practices in the pub sector such as sky high rents and wholesale prices.
"We can't let giant corporations dictate to our pubs."
The Campaign for Real Ale and the Federation of Small businesses both favour the amendment.
John Allan, national chairman of the Federation of Small Businesses, said: "It's time for more choice in our pubs and a fairer deal for publicans."
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