Nick Clegg: 'It's not in the national interest'
23 January 2013 Last updated at 10:54 GMT
David Cameron has said the British people must "have their say" on Europe as he pledged an in/out referendum if the Conservatives win the election.
The prime minister said he wanted to renegotiate the UK's relationship with the EU, before asking people to vote.
The Deputy Prime Minister, Nick Clegg, says the Prime Minister's promise will "hit growth and jobs".