Brexit campaigner Nigel Farage has said that he was increasingly concerned that a vote for Britain to leave the European Union could be overturned by a powerful group of the bloc's supporters.
In an interview with Britain's Observer newspaper, Mr Farage, former head of the eurosceptic UK Independence Party, said a well-organised and funded group of campaigners that wants to remain in the EU was drowning out those who want to leave.
"The Remain side are making all the running," he said.
"They have a majority in parliament, and unless we get ourselves organised we could lose the historic victory that was Brexit."
Last week, Mr Farage said he was warming to the idea of holding a second vote on Britain's membership of the EU to settle the argument - an idea written off by other Brexit campaigners who urged the government to press on with exit talks with the bloc.
Today, Labour party leader Jeremy Corbyn said that his party is not supporting or calling for a second referendum on EU membership.
Speaking on ITV's Peston on Sunday show, Mr Corbyn said: "We are not supporting or calling for a second referendum; what we've called for is a meaningful vote in parliament."
In 2016, Britons voted 52%-48% in favour of ending its membership of the EU.
British Prime Minister Theresa May has ruled out a second referendum, saying her government was seeking an amicable divorce with the EU which will safeguard the economy and enable Britain to secure trade deals with other countries.
But some Brexit campaigners fear her approach has led to the watering down of several of their demands, including the ability to reduce immigration and to reclaim sovereignty by leaving the jurisdiction of the European Court of Justice.
Several pro-EU campaigners say the need for a second referendum has become more pressing because public opinion is showing some signs of turning against Brexit as the difficulty of negotiations to leave the bloc becomes increasingly clear.