German Chancellor Angela Merkel formally invited her fellow EU leaders to the Brussels summit starting Thursday, with the message that "only together will we succeed in resolving the issues before us."
"The European public now expects us to put the necessary reforms of the union in hand," she said. "Following our consultations over the last few months the time has now come to set out the roadmap for the impending reform of the treaties."
However the Polish position remains "unchanged, we have not seen any accommodation," a spokesman for the German EU presidency said in Berlin.
Poland strongly objects to the voting system proposed by Germany which will be discussed at the summit, aimed at working out the broad lines of a new treaty to replace the constitution rejected by French and Dutch voters in 2005.
Warsaw believes "double majority" voting, under which agreement by 55 percent of member states representing 65 percent of the EU population would be required for new rules, would favor big states like Germany.
Possibility of compromise?
EU Commission Chief Jose Manuel Barroso held an hour-long telephone conversation with Polish Prime Minister Jaroslaw Kaczynski Wednesday seeking a compromise.
After the talks, a Polish spokesman said both men "see the possibility of compromise."
He hinted that modifications, or a delay, to the double majority voting plan might be enough to persuade Warsaw to get in line.
Czech Premier Mirek Topolanek, the only backer of the Polish demand, meanwhile said Wednesday that his country would not veto an agreement at the summit even if Poland fails to get the requested changes included.
Pressure from both sides
Britain, the other major opponent to some of Merkel's suggestions was still talking tough Wednesday.
"If it comes down to deal or no deal at this European Council the UK government is clear ... no deal is better than buying any old pig in a poke," Foreign Secretary Margaret Beckett said.
British Prime Minister Tony Blair insists he will not cede national control over foreign policy, the judicial and police system or tax and social security rules, while refusing to give legal force to an EU charter of fundamental rights.
Spanish Foreign Minister Miguel Angel Moratinos said he was sure the EU states could reach agreement on a new treaty but said he was "very worried" about British opposition to an EU-wide foreign policy.
At the other end of the spectrum, Luxembourg's Prime Minister Jean-Claude Juncker threatened to reject the new EU treaty if it did not correspond with crucial elements of the current proposal for a constitution, putting pressure on Germany from another side.
Germany, which holds the EU presidency until the end of the month, on Tuesday handed its EU partners a draft mandate for the intergovernmental conference.
The draft scraps reference to the EU flag and anthem, items guaranteed to raise the hackles of euroskeptics.
It also avoids some controversial terminology. The new "reform treaty" would amend existing EU treaties rather than replace them. The word "constitution" has been dropped.
Germany insists on an EU "foreign minister," but a new job title has to be agreed on. This is unlikely to satisfy Britain.
For Britain, which also opposes more qualified majority voting in judicial matters, preferring instead unanimous decision-making, Germany offered a clause for countries that choose not to participate.
The German draft also provides for national parliaments to be given up to eight weeks to examine draft laws, satisfying a demand by the Netherlands.
Any draft mandate for a treaty will then go to an intergovernmental conference, which official say is likely to start in July, for several months of discussion.