A report presented by France and Germany Tuesday calls on the EU to pass a raft of reforms to make it ready by 2030 to accept new members such as Ukraine.
Experts from the two European heavyweights drew up the proposals aimed at streamlining the way the bloc works as Brussels eyes its biggest wave of expansion in decades.
The report - which does not represent the official German or French positions - will feed into protracted debates among the EU's 27 member states about potential reforms.
Russia's war on Ukraine has breathed new energy into the stalled process to take on new members from the Balkans and eastern Europe.
"It is clear the enlargement of the EU is in all our interests," said Germany's Europe minister Anna Luhrmann, who was presenting the report in Brussels with her French counterpart.
"We must therefore start now to do everything possible to ensure that the EU is ready for this enlargement."
Ukraine - along with Moldova - became candidates to join last year and are hoping to get the green light to start accession talks before the end of 2023.
Accepting Kyiv would mark a major sea-change, as Ukraine, a country of over 40 million people, would become the EU's fifth largest member.
In the report, the think tank experts called to "set the goal for the EU to be ready for enlargement by 2030".
To get there the bloc should move to drop the need for unanimity required on key issues such as taxation, finances and foreign affairs in favour of a qualified majority, they said.
"Governments have acknowledged that further enlargement without proper institutional reforms would make it even harder - if not impossible - for the EU to take decisions," the report said.
The experts recommend potential opt-outs that would allow country's wary of dropping their veto powers to not go along with decisions they oppose.
The report also envisions trimming Brussel's notorious bureaucracy by cutting the number of commissioners put forward by member states in the EU's executive.
If some member states do not want to go along with changing the EU's treaties, then the experts say a "coalition of the willing" could push on with reforms.
This could then lead to four tiers of European integration involving the "inner circle", the broader EU, associate members and a looser political community.
EU members in eastern Europe pressing more strongly for Ukraine to get membership are wary that calls for fundamental reforms could be used to hold up enlargement.
European Commissioner chief Ursula von der Leyen in her annual state of the union speech last week insisted the bloc should not wait for treaty change before accepting new members.