Poland fought a successful rearguard battle to delay the new population-based voting system until 2017 and on Monday pushed to incorporate in the treaty a provision allowing states without a blocking minority to delay EU decisions for several months.
"I am very optimistic. There is just a small step towards an agreement," Polish Foreign Minister Anna Fotyga told reporters.
Other states want the so-called Ioannina Compromise confined to a less binding, perhaps time-limited political declaration.
But Luxembourg Foreign Minister Jean Asselborn suggested Poland's demand could be met.
"One possibility would be to put Ioannina in a protocol, which could be changed without having to take apart the whole treaty," he said.
Italy reiterated its anger at losing parity with France and Britain in the redistribution of European Parliament seats and wants that issue separated from the treaty and negotiated at a later date. The EU assembly proposed the reallocation to take account of population changes, with Spain the biggest gainer.
"I don't have a final ideal. I cannot anticipate what the solution will be," Antunes said of Italy's demands.
New member Bulgaria raised the stakes at the last minute by demanding that the European single currency be written as "evro" in its Cyrillic alphabet, as it was in its accession treaty. The European Central Bank opposes alternative spellings of the euro.
Sofia dropped a threat to block the signing of an accord on closer ties between the EU and Montenegro on Monday after EU ambassadors issued a declaration recognising a "linguistic-technical problem" and promising to solve it soon.
Austria reiterated its demand to formulate the treaty in such a way that it does not prevent it from limiting the number of foreign students at its universities. The country has faces flood of mostly German students at Vienna universities.
Britain said it was satisfied with various opt-outs it had negotiated from the treaty's provisions on social and home affairs issues. "People will see that the British national interest has been very clearly defended," said Foreign Minister David Milliband.
