Liberal Democrat leader Nick Clegg has used his New Year message to reiterate his pro-European Union stance ahead of the European Parliament elections and a referendum on UK membership.
The Deputy Prime Minister said: "In a few months, I'm going to ask you to make a different choice. The Liberal Democrats are Britain's Party of 'In'. Not because we're in love with the EU, or we think it's perfect but because being in Europe means jobs, trade and prosperity".
Mr Clegg - who appointed former Scottish Secretary Michael Moore as his adviser on European business as part of the campaign to promote the pro-EU case - said the UK's biggest firms calculated membership was worth £3,000 per household per year.
"So in May, be for 'In'," he declared. "Don't wait for a referendum. Don't wait for the general election. Make your voice heard now".
Nick Clegg warned voters they would jeopardise Britain's economic recovery and put jobs at risk if they vote for any party other than the Liberal Democrats in May's European Parliament elections.
The Deputy Prime Minister used his New Year message to deliver a boldly pro-EU speech in a bid to confront head on the mounting threat of the UK Independence Party.
Mr Clegg is opposed to his Conservative coalition colleague David Cameron's promise of an in/out referendum by 2017 and he accuses Labour of failing to make the case for continued membership sufficiently strongly.
He said: "Ukip want out. The Conservatives are flirting with exit. And Labour just don't have the courage of their convictions on this. All three would put narrow political interests ahead of the national economic interest."
Labour leader Ed Miliband has signalled his determination to keep up the pressure on the Government over the squeeze on living standards, despite growing signs the economy is finally beginning to pick up strength.
In his New Year message, the Mr Miliband highlighted the plight of families still struggling to make ends meet in what he called the "biggest cost-of-living crisis in a generation".
He sought to counter the increasing optimism of the Conservatives about the state of the economy by accusing them of ignoring the fact that many people were still no better off.
He said: "We are in the midst of the biggest cost-of-living crisis in a generation.
"Whether it's people being unable to afford the weekly shop or worried about the gas and electric bill - or saying 'I have always thought of myself as reasonably well off but I'm really having trouble making ends meet'."