David Cameron today indicated he could introduce a Bill in this parliament to pave the way for a referendum on Britain's membership of the European Union.
The Prime Minister said he was prepared to consider any measure to strengthen his commitment to stage an in/out referendum on the EU after the next general election.
Asked whether that could include introducing a Bill in this parliament, he told BBC Radio 4's The World At One: "I think we need to demonstrate absolutely that we are serious about this referendum.
"Anything we can to do to strengthen that offer I am prepared to consider."
His comments come at a time when the Conservatives are under pressure from the the UK Independence Party.
Mr Cameron announced in January that he would seek to renegotiate the terms of Britain's EU membership and then put them to a public vote in an in/out referendum.