The Shadow Chancellor, George Osborne, called for a referendum on a new EU treaty if there is any transfer of power to Brussels.
He said: "We've said if the deal they sign up to, that Gordon Brown will be tied in to, that transfers power to Europe, European institutions, then there should be a referendum.
"This is not an extraordinary position to adopt, this is what we were promised by Tony Blair and Gordon Brown, just a couple of years ago.
"And it would be extraordinary, for a new Prime Minister who has promised to listen more, to engage with the public, to get away from all the disconnect which has grown up between the British government and the British people.
"It would be extraordinary if Gordon Brown's first act would be to rule out giving the British public a say in something as fundamental as the transfer of power to the EU."
Brown not Blair
George Osborne went on to say that Gordon Brown should be in Brussels to take part in the treaty negotiations: "You do have this extraordinary situation where a British Prime Minister is about to take over and his predecessor will have signed him up to some kind of treaty just a few days before.
"Really, Gordon Brown should be sitting at that European Council rather than Tony Blair, but the Labour Party have mishandled this transition and so be it."
Speak up - Stand up
He also spoke about the next phase of the Conservative Party's policy making process - the 'Speak Up, Stand Up' campaign which is being launched next week.
"We want to open up our policy process and we're setting out how we're going to do that next week with our Speak Up, Stand Up campaign and take the nation's despatch boxes, you know, get the whole country involved in policy making.
"Because in every other area of your life, you expect a say over how decisions are taken that affect you. You expect a choice in things..."
He was asked what would happen if he, instead of having a top down approach, had a bottom up approach and the Tory grass roots say, "we want grammar schools"?
He replied: I'll tell you, as a Member of Parliament, I have had one letter on grammar schools in the last five weeks, I promise you, one letter.
"So I don't see, in areas like mine, where there are no grammar schools, a great clamouring for a return to the '11 plus'."
The Politics Show Sunday 17 June 2007 at 12:00 BST on BBC One.
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