David Cameron will today express his support for the European Union but insist it must end the "culture of hopelessness" that haunts it at the moment.
The Conservative leader will call on his party to be "the champions for real change in Europe" and face up to the union's damaging economic and environmental policies.
"We are a new generation. We have no time for the culture of hopelessness that has plagued the way the EU has often attempted to address the big global challenges we face," he will tell Tory MEPs in Brussels today.
"It's because we want to see a future for the EU and believe in a strong Europe that we want to make the EU confront its failings."
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Mr Cameron is in the Belgian capital for talks with European Commission president Jose Manuel Barroso, and the commissioners for trade and the environment, but he will also use the opportunity to reassure Tory MEPs of his aims in the EU.
He has faced criticism over his Europe policy over the past few months, namely because of the decision to pull the Tories out of the centre-right coalition in the European parliament, the European People's Party (EPP), and form a new grouping.
The announcement was met with dismay by many Conservative MEPs, and last month Ed Balls, Gordon Brown's closest political ally, cited this decision as proof that Mr Cameron was the most "anti-European Tory leader" ever.
In a speech to MEPs today, however, Mr Cameron will insist that he believes in the power of the EU, but stress that it must address certain key issues, including the fact that it has not had its accounts signed off for 11 years.
He will note that last year, the EU made tackling poverty in Africa a priority, but warn that many of its policies - in particular the failure to reform the common agricultural policy (CAP) of farm subsidies - are actually making poverty worse.
On the environment, Europe's target under the Kyoto protocol is to cut carbon emission by eight per cent by 2012, but Mr Cameron will warn that with just six years to go, emissions are down less than one per cent on 1990 levels.
And on the economy, he will note that in 2000, European leaders said they would make the union the most competitive knowledge-based economy in the world by 2010. But since 1998, he says new EU regulations have cost business £37 billion.
"It's not good enough and it's got to change," he will say, adding: "It is time to drive forward a new agenda in Europe - looking outwards to the world, flexible, competitive - ready to face the challenges of globalisation in the 21st century."
Diana Wallis MEP, leader of the Liberal Democrats in the European parliament, welcomed Mr Cameron's acknowledgment of the EU's global role, adding: "Better late than never."