Speaking to the Daily Mail, Mr Cameron said: "While this treaty is still being debated and other countries are having referendums or whatever, it's still open for Britain to have a referendum. Let's focus on the need for a referendum now.
"If we reach circumstances where the whole treaty has been not only ratified but implemented, that is not a situation we would be content with.
"We wouldn't let matters rest there. "We think the treaty is wrong because it passes too much power from Westminster to Brussels. We would address that issue at the time."
But Mr Murphy said: "... The Tories' position would lead ultimately to the disaster of Britain's withdrawal from the EU, and in the meantime would be a recipe for years of uncertainty and instability that would be damaging to British business, British jobs and British prosperity."
Full coverage : The Press Association http://ukpress.google.com/article/ALeqM5i33mqL39x8Nsi6I2TYkxUGeyIRPQ
David Cameron in strong signal on EU treatyTelegraph.co.uk - Dec 30, 2007
David Cameron: I'll tear up the EU treaty even if it has been signedThis is London - Dec 30, 2007