The British and Dutch prime ministers have said the European Union does not need a "whole new constitution", just limited changes to existing treaties.
The leaders said the EU needed to focus on other things
Tony Blair and Jan Peter Balkenende said the focus should be on changes that made the EU work better.
The Netherlands followed France in voting against a draft constitution in 2005, plunging the EU into crisis.
Mr Blair promised to hold a referendum in the UK, but officials say no vote is needed for a simple "amending" treaty.
"I think people can identify very clearly the things that give rise to a European super-state that we do not want... and those things which are necessary to make Europe work more effectively," Mr Blair said, after talks in London.
He added: "There's all the difference in the world between a constitutional treaty that is an attempt to consolidate... to write all the rules of the European Union, to give rise to a whole new set of legal principles - and an amending treaty within the existing European treaties that makes the rules work more effectively."
The German government, which holds the EU's rotating presidency, will present EU leaders in June with a roadmap for the adoption of a new constitutional treaty.
It has said it wants to preserve as much of the old constitution as possible, and has support from 17 other states which have all ratified, or nearly ratified, the text.
Mr Blair said it was important to recognise that the UK and the Netherlands were not the only countries that "really will have a difficulty with a constitutional treaty rather than a treaty, say, in the tradition of the treaty that we negotiated in Amsterdam some 10 years ago."
Mr Balkenende said the EU needed rule changes to increase democracy and efficiency.
An amending treaty could include a clarification of the division of powers between the European Commission and member states, a bigger role for national parliaments and rules for further enlargement of the EU, he said.
He added: "If we do not have the characteristics of a constitution, that is also relevant to the question of do you have a referendum or not."
Mr Blair agreed that a bigger role for national parliaments would help tackle fears that the treaty was helping to create a superstate.
Derek Scott, deputy chairman of Eurosceptic pressure group Open Europe, said: "The government are spinning that the new treaty will no longer be called a constitution.
"But everyone knows it is likely to contain exactly the same proposals: an EU president, EU foreign minister, and plans to reduce our right to say no to EU regulations.
"Just changing the name isn't going to fool anyone, and we intend to hold the government to its promise to hold a referendum."