Reuters, London :British Prime Minister David Cameron on Tuesday said there was only a “pretty slim” chance that he could bring forward to 2015 a referendum on the country’s membership of the European Union which he wants to hold if he wins a national election in May.Cameron has promised to renegotiate Britain’s relationship with Europe on issues such as immigration and then hold a referendum by 2017, hoping to prevent a rise in Eurosceptic sentiment which has pushed some Conservative party voters towards the anti-EU UK Independence Party (UKIP).UKIP leader Nigel Farage has said his party would do a deal to allow Cameron to form a government if, as expected, the election fails to produce a clear winner. But Farage said the price of such a deal would be a referendum before the end of the year.In an interview on ITV’s “Good Morning Britain” TV show, Cameron poured cold water on that prospect.”The sooner that (EU) renegotiation can get done the better, but frankly the chances of doing that inside 2015 after an election in May are pretty slim,” he said. He said he would not consider any deal making until after the election.