Tory MPs get tough on EU
Dozens of Conservative MPs are demanding that David Cameron seizes back control of employment and social laws from Brussels.
The Fresh Start group of Conservative backbenchers will throw down the gauntlet on Europe as they publish their 'manifesto' on Wednesday.
As well as calling for a repatriation of all social and employment law, the group want Mr Cameron to stop European nationals from claiming benefits in this country.
Their publication, backed by Foreign Secretary William Hague, will warn that "the status quo is no longer an option" and demand "a new and different relationship" with the European Union, according to reports.
But Mr Cameron is also facing pressure from elsewhere not to take a hardline on Europe when he delivers his key speech on Friday.
Sir Nigel Sheinwald, Britain's ambassador to Washington until last year and before that the senior British diplomat in Brussels, has told of his concerns in an interview to The Guardian.
He said: "I just cannot see any logical basis for thinking a move to the sidelines, or particularly a move out of Europe, would be anything other than diminishing to UK's capacity, standing, influence, ability to get things done and capacity to build coalitions internationally."
It comes hours after Nick Clegg warned that the uncertainty created by the row over Britain's EU membership would have "a chilling effect" on growth.
Speaking on the Today programme, the Deputy Prime Minister said the Government had already committed to a referendum on any major EU treaty change."We're actually the only government - with Liberal Democrats, with my full support - to give the clarity in law about when a referendum takes place," he said.
"All I'm saying in addition to that is don't, given - we've given that clarity, we've given that certainty that there will be a referendum triggered in the future in those circumstances don't think it is wise to add to that with a degree of uncertainty which I believe would have a chilling effect on jobs and growth in this country."
Asked to respond to the 'chilling effect' remarks, Downing Street said: "The Prime Minister's view is that it is absolutely in the national interest to be taking a lead in this debate".
No.10 has also confirmed that the Deputy Prime Minister would be shown Mr Cameron's speech on Europe "before he gives it".
However, only Tory Cabinet ministers will be personally briefed on the speech by Mr Cameron at a meeting tomorrow.