Liberal Democrats hint Cameron's EU referendum plan negotiable

By William James LONDON (Reuters) - Britain's Liberal Democrats, possible kingmakers after a close election in three weeks' time, hinted they could back some form of Prime Minister David Cameron's plan to hold an EU membership referendum in return for unspecified concessions. Unveiling their policy manifesto on Wednesday, the centre-left party, the junior partner in a coalition with Cameron's Conservatives since 2010, set out five priority areas they signalled were non-negoti