The Labour leader Ed Miliband is asking the Prime Minister to give guarantees that he will recommend that Britain should leave the European Union if he does not get the settlement he wants.
David Cameron responded saying: "I want Britain to be part of a reformed and successful European Union."
To the surprise of many Lib Dems, Nick Clegg appears to have played down the importance of the Coalition's divide on an in-out referendum.
Business leaders in Davos are worried about the Prime Minister's pledge to put Britain's membership of the European Union to a referendum.
With some in France keen to "roll out the red carpet" for a British exit, Germans favouring decentralisation welcome EU renegotiation talks.