David Cameron has rejected the calls of senior conservatives wanting to leave the European Union, saying that it was "extraordinary" to abandon hope before he had started to renegotiate Britain's membership terms.

The Prime Minister gave a speech on Europe earlier this year in which he said if the Conservatives were relected at the next general election, a referendum on exiting the EU would be offered to the British public by 2017.

But in the past few days Lord Lawson and Michael Portillo have called for Britain to leave the European Union, with two members of Cameron's cabinet, Education Secretary Michael Gove and Defence Secretary Philip Hammond, have come out saying that they would vote to leave the EU if a referendum on British membership were held now.

Cameron, who is in Washington DC to meet with US President Barack Obama, was speaking as Tory MPs look set to force a Commons vote on amending the Queen's speech by including a bill on an EU referendum. The Prime Minister has said he would campaign to stay in the European Union if he could change Britain's relationship with the EU, saying that people, "Shouldn't give up before a negotiation has started."

The Commons amendment is highly unlikely to be passed, because Labour, the Lib Dems and many Conservatives will vote against it or abstain.

Written and presented by Alfred Joyner